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2022-04-20KVM: Prevent module exit until all VMs are freedDavid Matlack1-0/+13
commit 5f6de5cbebee925a612856fce6f9182bb3eee0db upstream. Tie the lifetime the KVM module to the lifetime of each VM via kvm.users_count. This way anything that grabs a reference to the VM via kvm_get_kvm() cannot accidentally outlive the KVM module. Prior to this commit, the lifetime of the KVM module was tied to the lifetime of /dev/kvm file descriptors, VM file descriptors, and vCPU file descriptors by their respective file_operations "owner" field. This approach is insufficient because references grabbed via kvm_get_kvm() do not prevent closing any of the aforementioned file descriptors. This fixes a long standing theoretical bug in KVM that at least affects async page faults. kvm_setup_async_pf() grabs a reference via kvm_get_kvm(), and drops it in an asynchronous work callback. Nothing prevents the VM file descriptor from being closed and the KVM module from being unloaded before this callback runs. Fixes: af585b921e5d ("KVM: Halt vcpu if page it tries to access is swapped out") Fixes: 3d3aab1b973b ("KVM: set owner of cpu and vm file operations") Cc: stable@vger.kernel.org Suggested-by: Ben Gardon <bgardon@google.com> [ Based on a patch from Ben implemented for Google's kernel. ] Signed-off-by: David Matlack <dmatlack@google.com> Message-Id: <20220303183328.1499189-2-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-01-27KVM: do not allow mapping valid but non-reference-counted pagesNicholas Piggin1-2/+17
commit f8be156be163a052a067306417cd0ff679068c97 upstream. It's possible to create a region which maps valid but non-refcounted pages (e.g., tail pages of non-compound higher order allocations). These host pages can then be returned by gfn_to_page, gfn_to_pfn, etc., family of APIs, which take a reference to the page, which takes it from 0 to 1. When the reference is dropped, this will free the page incorrectly. Fix this by only taking a reference on valid pages if it was non-zero, which indicates it is participating in normal refcounting (and can be released with put_page). This addresses CVE-2021-22543. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Tested-by: Paolo Bonzini <pbonzini@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-01-27KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped()Sean Christopherson1-1/+1
commit a9545779ee9e9e103648f6f2552e73cfe808d0f4 upstream. Use kvm_pfn_t, a.k.a. u64, for the local 'pfn' variable when retrieving a so called "remapped" hva/pfn pair. In theory, the hva could resolve to a pfn in high memory on a 32-bit kernel. This bug was inadvertantly exposed by commit bd2fae8da794 ("KVM: do not assume PTE is writable after follow_pfn"), which added an error PFN value to the mix, causing gcc to comlain about overflowing the unsigned long. arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function ‘hva_to_pfn_remapped’: include/linux/kvm_host.h:89:30: error: conversion from ‘long long unsigned int’ to ‘long unsigned int’ changes value from ‘9218868437227405314’ to ‘2’ [-Werror=overflow] 89 | #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2) | ^ virt/kvm/kvm_main.c:1935:9: note: in expansion of macro ‘KVM_PFN_ERR_RO_FAULT’ Cc: stable@vger.kernel.org Fixes: add6a0cd1c5b ("KVM: MMU: try to fix up page faults before giving up") Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210208201940.1258328-1-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-01-27KVM: do not assume PTE is writable after follow_pfnPaolo Bonzini1-3/+12
commit bd2fae8da794b55bf2ac02632da3a151b10e664c upstream. In order to convert an HVA to a PFN, KVM usually tries to use the get_user_pages family of functinso. This however is not possible for VM_IO vmas; in that case, KVM instead uses follow_pfn. In doing this however KVM loses the information on whether the PFN is writable. That is usually not a problem because the main use of VM_IO vmas with KVM is for BARs in PCI device assignment, however it is a bug. To fix it, use follow_pte and check pte_write while under the protection of the PTE lock. The information can be used to fail hva_to_pfn_remapped or passed back to the caller via *writable. Usage of follow_pfn was introduced in commit add6a0cd1c5b ("KVM: MMU: try to fix up page faults before giving up", 2016-07-05); however, even older version have the same issue, all the way back to commit 2e2e3738af33 ("KVM: Handle vma regions with no backing page", 2008-07-20), as they also did not check whether the PFN was writable. Fixes: 2e2e3738af33 ("KVM: Handle vma regions with no backing page") Reported-by: David Stevens <stevensd@google.com> Cc: 3pvd@google.com Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [OP: backport to 4.19, adjust follow_pte() -> follow_pte_pmd()] Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backport to 4.9: follow_pte_pmd() does not take start or end parameters] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-23kvm: check tlbs_dirty directlyLai Jiangshan1-2/+1
commit 88bf56d04bc3564542049ec4ec168a8b60d0b48c upstream In kvm_mmu_notifier_invalidate_range_start(), tlbs_dirty is used as: need_tlb_flush |= kvm->tlbs_dirty; with need_tlb_flush's type being int and tlbs_dirty's type being long. It means that tlbs_dirty is always used as int and the higher 32 bits is useless. We need to check tlbs_dirty in a correct way and this change checks it directly without propagating it to need_tlb_flush. Note: it's _extremely_ unlikely this neglecting of higher 32 bits can cause problems in practice. It would require encountering tlbs_dirty on a 4 billion count boundary, and KVM would need to be using shadow paging or be running a nested guest. Cc: stable@vger.kernel.org Fixes: a4ee1ca4a36e ("KVM: MMU: delay flush all tlbs on sync_page path") Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> Message-Id: <20201217154118.16497-1-jiangshanlai@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [sudip: adjust context] Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-01KVM: fix overflow of zero page refcount with ksm runningZhuang Yanying1-0/+1
[ Upstream commit 7df003c85218b5f5b10a7f6418208f31e813f38f ] We are testing Virtual Machine with KSM on v5.4-rc2 kernel, and found the zero_page refcount overflow. The cause of refcount overflow is increased in try_async_pf (get_user_page) without being decreased in mmu_set_spte() while handling ept violation. In kvm_release_pfn_clean(), only unreserved page will call put_page. However, zero page is reserved. So, as well as creating and destroy vm, the refcount of zero page will continue to increase until it overflows. step1: echo 10000 > /sys/kernel/pages_to_scan/pages_to_scan echo 1 > /sys/kernel/pages_to_scan/run echo 1 > /sys/kernel/pages_to_scan/use_zero_pages step2: just create several normal qemu kvm vms. And destroy it after 10s. Repeat this action all the time. After a long period of time, all domains hang because of the refcount of zero page overflow. Qemu print error log as follow: … error: kvm run failed Bad address EAX=00006cdc EBX=00000008 ECX=80202001 EDX=078bfbfd ESI=ffffffff EDI=00000000 EBP=00000008 ESP=00006cc4 EIP=000efd75 EFL=00010002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0 ES =0010 00000000 ffffffff 00c09300 DPL=0 DS [-WA] CS =0008 00000000 ffffffff 00c09b00 DPL=0 CS32 [-RA] SS =0010 00000000 ffffffff 00c09300 DPL=0 DS [-WA] DS =0010 00000000 ffffffff 00c09300 DPL=0 DS [-WA] FS =0010 00000000 ffffffff 00c09300 DPL=0 DS [-WA] GS =0010 00000000 ffffffff 00c09300 DPL=0 DS [-WA] LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy GDT= 000f7070 00000037 IDT= 000f70ae 00000000 CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000 DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 DR6=00000000ffff0ff0 DR7=0000000000000400 EFER=0000000000000000 Code=00 01 00 00 00 e9 e8 00 00 00 c7 05 4c 55 0f 00 01 00 00 00 <8b> 35 00 00 01 00 8b 3d 04 00 01 00 b8 d8 d3 00 00 c1 e0 08 0c ea a3 00 00 01 00 c7 05 04 … Meanwhile, a kernel warning is departed. [40914.836375] WARNING: CPU: 3 PID: 82067 at ./include/linux/mm.h:987 try_get_page+0x1f/0x30 [40914.836412] CPU: 3 PID: 82067 Comm: CPU 0/KVM Kdump: loaded Tainted: G OE 5.2.0-rc2 #5 [40914.836415] RIP: 0010:try_get_page+0x1f/0x30 [40914.836417] Code: 40 00 c3 0f 1f 84 00 00 00 00 00 48 8b 47 08 a8 01 75 11 8b 47 34 85 c0 7e 10 f0 ff 47 34 b8 01 00 00 00 c3 48 8d 78 ff eb e9 <0f> 0b 31 c0 c3 66 90 66 2e 0f 1f 84 00 0 0 00 00 00 48 8b 47 08 a8 [40914.836418] RSP: 0018:ffffb4144e523988 EFLAGS: 00010286 [40914.836419] RAX: 0000000080000000 RBX: 0000000000000326 RCX: 0000000000000000 [40914.836420] RDX: 0000000000000000 RSI: 00004ffdeba10000 RDI: ffffdf07093f6440 [40914.836421] RBP: ffffdf07093f6440 R08: 800000424fd91225 R09: 0000000000000000 [40914.836421] R10: ffff9eb41bfeebb8 R11: 0000000000000000 R12: ffffdf06bbd1e8a8 [40914.836422] R13: 0000000000000080 R14: 800000424fd91225 R15: ffffdf07093f6440 [40914.836423] FS: 00007fb60ffff700(0000) GS:ffff9eb4802c0000(0000) knlGS:0000000000000000 [40914.836425] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [40914.836426] CR2: 0000000000000000 CR3: 0000002f220e6002 CR4: 00000000003626e0 [40914.836427] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [40914.836427] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [40914.836428] Call Trace: [40914.836433] follow_page_pte+0x302/0x47b [40914.836437] __get_user_pages+0xf1/0x7d0 [40914.836441] ? irq_work_queue+0x9/0x70 [40914.836443] get_user_pages_unlocked+0x13f/0x1e0 [40914.836469] __gfn_to_pfn_memslot+0x10e/0x400 [kvm] [40914.836486] try_async_pf+0x87/0x240 [kvm] [40914.836503] tdp_page_fault+0x139/0x270 [kvm] [40914.836523] kvm_mmu_page_fault+0x76/0x5e0 [kvm] [40914.836588] vcpu_enter_guest+0xb45/0x1570 [kvm] [40914.836632] kvm_arch_vcpu_ioctl_run+0x35d/0x580 [kvm] [40914.836645] kvm_vcpu_ioctl+0x26e/0x5d0 [kvm] [40914.836650] do_vfs_ioctl+0xa9/0x620 [40914.836653] ksys_ioctl+0x60/0x90 [40914.836654] __x64_sys_ioctl+0x16/0x20 [40914.836658] do_syscall_64+0x5b/0x180 [40914.836664] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [40914.836666] RIP: 0033:0x7fb61cb6bfc7 Signed-off-by: LinFeng <linfeng23@huawei.com> Signed-off-by: Zhuang Yanying <ann.zhuangyanying@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01KVM: fix memory leak in kvm_io_bus_unregister_dev()Rustam Kovhaev1-9/+12
[ Upstream commit f65886606c2d3b562716de030706dfe1bea4ed5e ] when kmalloc() fails in kvm_io_bus_unregister_dev(), before removing the bus, we should iterate over all other devices linked to it and call kvm_iodevice_destructor() for them Fixes: 90db10434b16 ("KVM: kvm_io_bus_unregister_dev() should never fail") Cc: stable@vger.kernel.org Reported-and-tested-by: syzbot+f196caa45793d6374707@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=f196caa45793d6374707 Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20200907185535.233114-1-rkovhaev@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-11KVM: Check for a bad hva before dropping into the ghc slow pathSean Christopherson1-6/+6
commit fcfbc617547fc6d9552cb6c1c563b6a90ee98085 upstream. When reading/writing using the guest/host cache, check for a bad hva before checking for a NULL memslot, which triggers the slow path for handing cross-page accesses. Because the memslot is nullified on error by __kvm_gfn_to_hva_cache_init(), if the bad hva is encountered after crossing into a new page, then the kvm_{read,write}_guest() slow path could potentially write/access the first chunk prior to detecting the bad hva. Arguably, performing a partial access is semantically correct from an architectural perspective, but that behavior is certainly not intended. In the original implementation, memslot was not explicitly nullified and therefore the partial access behavior varied based on whether the memslot itself was null, or if the hva was simply bad. The current behavior was introduced as a seemingly unintentional side effect in commit f1b9dd5eb86c ("kvm: Disallow wraparound in kvm_gfn_to_hva_cache_init"), which justified the change with "since some callers don't check the return code from this function, it sit seems prudent to clear ghc->memslot in the event of an error". Regardless of intent, the partial access is dependent on _not_ checking the result of the cache initialization, which is arguably a bug in its own right, at best simply weird. Fixes: 8f964525a121 ("KVM: Allow cross page reads and writes from cached translations.") Cc: Jim Mattson <jmattson@google.com> Cc: Andrew Honig <ahonig@google.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-28KVM: MMU: Do not treat ZONE_DEVICE pages as being reservedSean Christopherson1-3/+23
commit a78986aae9b2988f8493f9f65a587ee433e83bc3 upstream. Explicitly exempt ZONE_DEVICE pages from kvm_is_reserved_pfn() and instead manually handle ZONE_DEVICE on a case-by-case basis. For things like page refcounts, KVM needs to treat ZONE_DEVICE pages like normal pages, e.g. put pages grabbed via gup(). But for flows such as setting A/D bits or shifting refcounts for transparent huge pages, KVM needs to to avoid processing ZONE_DEVICE pages as the flows in question lack the underlying machinery for proper handling of ZONE_DEVICE pages. This fixes a hang reported by Adam Borowski[*] in dev_pagemap_cleanup() when running a KVM guest backed with /dev/dax memory, as KVM straight up doesn't put any references to ZONE_DEVICE pages acquired by gup(). Note, Dan Williams proposed an alternative solution of doing put_page() on ZONE_DEVICE pages immediately after gup() in order to simplify the auditing needed to ensure is_zone_device_page() is called if and only if the backing device is pinned (via gup()). But that approach would break kvm_vcpu_{un}map() as KVM requires the page to be pinned from map() 'til unmap() when accessing guest memory, unlike KVM's secondary MMU, which coordinates with mmu_notifier invalidations to avoid creating stale page references, i.e. doesn't rely on pages being pinned. [*] http://lkml.kernel.org/r/20190919115547.GA17963@angband.pl Reported-by: Adam Borowski <kilobyte@angband.pl> Analyzed-by: David Hildenbrand <david@redhat.com> Acked-by: Dan Williams <dan.j.williams@intel.com> Cc: stable@vger.kernel.org Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [sean: backport to 4.x; resolve conflict in mmu.c] Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
2019-11-16kvm: x86: mmu: Recovery of shattered NX large pagesJunaid Shahid1-1/+29
commit 1aa9b9572b10529c2e64e2b8f44025d86e124308 upstream. The page table pages corresponding to broken down large pages are zapped in FIFO order, so that the large page can potentially be recovered, if it is not longer being used for execution. This removes the performance penalty for walking deeper EPT page tables. By default, one large page will last about one hour once the guest reaches a steady state. Signed-off-by: Junaid Shahid <junaids@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 4.9: - Update another error path in kvm_create_vm() to use out_err_no_mmu_notifier - Adjust filename, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-16kvm: Add helper function for creating VM worker threadsJunaid Shahid1-0/+84
commit c57c80467f90e5504c8df9ad3555d2c78800bf94 upstream. Add a function to create a kernel thread associated with a given VM. In particular, it ensures that the worker thread inherits the priority and cgroups of the calling thread. Signed-off-by: Junaid Shahid <junaids@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 4.9: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-16kvm: Convert kvm_lock to a mutexJunaid Shahid1-9/+9
commit 0d9ce162cf46c99628cc5da9510b959c7976735b upstream. It doesn't seem as if there is any particular need for kvm_lock to be a spinlock, so convert the lock to a mutex so that sleepable functions (in particular cond_resched()) can be called while holding it. Signed-off-by: Junaid Shahid <junaids@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [bwh: Backported to 4.9: - Drop changes in kvm_hyperv_tsc_notifier(), vm_stat_clear(), vcpu_stat_clear(), kvm_uevent_notify_change() - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-09-21KVM: coalesced_mmio: add bounds checkingMatt Delco1-7/+10
commit b60fe990c6b07ef6d4df67bc0530c7c90a62623a upstream. The first/last indexes are typically shared with a user app. The app can change the 'last' index that the kernel uses to store the next result. This change sanity checks the index before using it for writing to a potentially arbitrary address. This fixes CVE-2019-14821. Cc: stable@vger.kernel.org Fixes: 5f94c1741bdc ("KVM: Add coalesced MMIO support (common part)") Signed-off-by: Matt Delco <delco@chromium.org> Signed-off-by: Jim Mattson <jmattson@google.com> Reported-by: syzbot+983c866c3dd6efa3662a@syzkaller.appspotmail.com [Use READ_ONCE. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-09-06KVM: arm/arm64: vgic-v2: Handle SGI bits in GICD_I{S,C}PENDR0 as WIMarc Zyngier3-2/+26
[ Upstream commit 82e40f558de566fdee214bec68096bbd5e64a6a4 ] A guest is not allowed to inject a SGI (or clear its pending state) by writing to GICD_ISPENDR0 (resp. GICD_ICPENDR0), as these bits are defined as WI (as per ARM IHI 0048B 4.3.7 and 4.3.8). Make sure we correctly emulate the architecture. Fixes: 96b298000db4 ("KVM: arm/arm64: vgic-new: Add PENDING registers handlers") Cc: stable@vger.kernel.org # 4.7+ Reported-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-09-06KVM: arm/arm64: vgic: Fix potential deadlock when ap_list is longHeyi Guo1-0/+7
[ Upstream commit d4a8061a7c5f7c27a2dc002ee4cb89b3e6637e44 ] If the ap_list is longer than 256 entries, merge_final() in list_sort() will call the comparison callback with the same element twice, causing a deadlock in vgic_irq_cmp(). Fix it by returning early when irqa == irqb. Cc: stable@vger.kernel.org # 4.7+ Fixes: 8e4447457965 ("KVM: arm/arm64: vgic-new: Add IRQ sorting") Signed-off-by: Zenghui Yu <yuzenghui@huawei.com> Signed-off-by: Heyi Guo <guoheyi@huawei.com> [maz: massaged commit log and patch, added Fixes and Cc-stable] Signed-off-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-07-21KVM: arm/arm64: vgic: Fix kvm_device leak in vgic_its_destroyDave Martin1-0/+1
[ Upstream commit 4729ec8c1e1145234aeeebad5d96d77f4ccbb00a ] kvm_device->destroy() seems to be supposed to free its kvm_device struct, but vgic_its_destroy() is not currently doing this, resulting in a memory leak, resulting in kmemleak reports such as the following: unreferenced object 0xffff800aeddfe280 (size 128): comm "qemu-system-aar", pid 13799, jiffies 4299827317 (age 1569.844s) [...] backtrace: [<00000000a08b80e2>] kmem_cache_alloc+0x178/0x208 [<00000000dcad2bd3>] kvm_vm_ioctl+0x350/0xbc0 Fix it. Cc: Andre Przywara <andre.przywara@arm.com> Fixes: 1085fdc68c60 ("KVM: arm64: vgic-its: Introduce new KVM ITS device") Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-03KVM: Reject device ioctls from processes other than the VM's creatorSean Christopherson1-0/+3
commit ddba91801aeb5c160b660caed1800eb3aef403f8 upstream. KVM's API requires thats ioctls must be issued from the same process that created the VM. In other words, userspace can play games with a VM's file descriptors, e.g. fork(), SCM_RIGHTS, etc..., but only the creator can do anything useful. Explicitly reject device ioctls that are issued by a process other than the VM's creator, and update KVM's API documentation to extend its requirements to device ioctls. Fixes: 852b6d57dc7f ("kvm: add device control API") Cc: <stable@vger.kernel.org> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-02-12kvm: fix kvm_ioctl_create_device() reference counting (CVE-2019-6974)Jann Horn1-1/+2
commit cfa39381173d5f969daf43582c95ad679189cbc9 upstream. kvm_ioctl_create_device() does the following: 1. creates a device that holds a reference to the VM object (with a borrowed reference, the VM's refcount has not been bumped yet) 2. initializes the device 3. transfers the reference to the device to the caller's file descriptor table 4. calls kvm_get_kvm() to turn the borrowed reference to the VM into a real reference The ownership transfer in step 3 must not happen before the reference to the VM becomes a proper, non-borrowed reference, which only happens in step 4. After step 3, an attacker can close the file descriptor and drop the borrowed reference, which can cause the refcount of the kvm object to drop to zero. This means that we need to grab a reference for the device before anon_inode_getfd(), otherwise the VM can disappear from under us. Fixes: 852b6d57dc7f ("kvm: add device control API") Cc: stable@kernel.org Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-09-26KVM: arm/arm64: Fix vgic init raceChristoffer Dall1-0/+4
[ Upstream commit 1d47191de7e15900f8fbfe7cccd7c6e1c2d7c31a ] The vgic_init function can race with kvm_arch_vcpu_create() which does not hold kvm_lock() and we therefore have no synchronization primitives to ensure we're doing the right thing. As the user is trying to initialize or run the VM while at the same time creating more VCPUs, we just have to refuse to initialize the VGIC in this case rather than silently failing with a broken VCPU. Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-08-24KVM: irqfd: fix race between EPOLLHUP and irq_bypass_register_consumerPaolo Bonzini1-5/+6
commit 9432a3175770e06cb83eada2d91fac90c977cb99 upstream. A comment warning against this bug is there, but the code is not doing what the comment says. Therefore it is possible that an EPOLLHUP races against irq_bypass_register_consumer. The EPOLLHUP handler schedules irqfd_shutdown, and if that runs soon enough, you get a use-after-free. Reported-by: syzbot <syzkaller@googlegroups.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-08-24KVM: arm/arm64: Drop resource size check for GICV windowArd Biesheuvel1-5/+0
[ Upstream commit ba56bc3a0786992755e6804fbcbdc60ef6cfc24c ] When booting a 64 KB pages kernel on a ACPI GICv3 system that implements support for v2 emulation, the following warning is produced GICV size 0x2000 not a multiple of page size 0x10000 and support for v2 emulation is disabled, preventing GICv2 VMs from being able to run on such hosts. The reason is that vgic_v3_probe() performs a sanity check on the size of the window (it should be a multiple of the page size), while the ACPI MADT parsing code hardcodes the size of the window to 8 KB. This makes sense, considering that ACPI does not bother to describe the size in the first place, under the assumption that platforms implementing ACPI will follow the architecture and not put anything else in the same 64 KB window. So let's just drop the sanity check altogether, and assume that the window is at least 64 KB in size. Fixes: 909777324588 ("KVM: arm/arm64: vgic-new: vgic_init: implement kvm_vgic_hyp_init") Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-07-25KVM/Eventfd: Avoid crash when assign and deassign specific eventfd in parallel.Lan Tianyu1-1/+5
commit b5020a8e6b54d2ece80b1e7dedb33c79a40ebd47 upstream. Syzbot reports crashes in kvm_irqfd_assign(), caused by use-after-free when kvm_irqfd_assign() and kvm_irqfd_deassign() run in parallel for one specific eventfd. When the assign path hasn't finished but irqfd has been added to kvm->irqfds.items list, another thead may deassign the eventfd and free struct kvm_kernel_irqfd(). The assign path then uses the struct kvm_kernel_irqfd that has been freed by deassign path. To avoid such issue, keep irqfd under kvm->irq_srcu protection after the irqfd has been added to kvm->irqfds.items list, and call synchronize_srcu() in irq_shutdown() to make sure that irqfd has been fully initialized in the assign path. Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Tianyu Lan <tianyu.lan@intel.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-07-22KVM: arm/arm64: Do not use kern_hyp_va() with kvm_vgic_global_stateMarc Zyngier1-1/+1
Commit 44a497abd621a71c645f06d3d545ae2f46448830 upstream. kvm_vgic_global_state is part of the read-only section, and is usually accessed using a PC-relative address generation (adrp + add). It is thus useless to use kern_hyp_va() on it, and actively problematic if kern_hyp_va() becomes non-idempotent. On the other hand, there is no way that the compiler is going to guarantee that such access is always PC relative. So let's bite the bullet and provide our own accessor. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: James Morse <james.morse@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-30kvm: Map PFN-type memory regions as writable (if possible)KarimAllah Ahmed1-2/+5
[ Upstream commit a340b3e229b24a56f1c7f5826b15a3af0f4b13e5 ] For EPT-violations that are triggered by a read, the pages are also mapped with write permissions (if their memory region is also writable). That would avoid getting yet another fault on the same page when a write occurs. This optimization only happens when you have a "struct page" backing the memory region. So also enable it for memory regions that do not have a "struct page". Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-22KVM: arm/arm64: VGIC/ITS: protect kvm_read_guest() calls with SRCU lockAndre Przywara1-7/+8
commit bf308242ab98b5d1648c3663e753556bef9bec01 upstream. kvm_read_guest() will eventually look up in kvm_memslots(), which requires either to hold the kvm->slots_lock or to be inside a kvm->srcu critical section. In contrast to x86 and s390 we don't take the SRCU lock on every guest exit, so we have to do it individually for each kvm_read_guest() call. Provide a wrapper which does that and use that everywhere. Note that ending the SRCU critical section before returning from the kvm_read_guest() wrapper is safe, because the data has been *copied*, so we don't need to rely on valid references to the memslot anymore. Cc: Stable <stable@vger.kernel.org> # 4.8+ Reported-by: Jan Glauber <jan.glauber@caviumnetworks.com> Signed-off-by: Andre Przywara <andre.przywara@arm.com> Acked-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-11KVM: mmu: Fix overlap between public and private memslotsWanpeng Li1-2/+1
commit b28676bb8ae4569cced423dc2a88f7cb319d5379 upstream. Reported by syzkaller: pte_list_remove: ffff9714eb1f8078 0->BUG ------------[ cut here ]------------ kernel BUG at arch/x86/kvm/mmu.c:1157! invalid opcode: 0000 [#1] SMP RIP: 0010:pte_list_remove+0x11b/0x120 [kvm] Call Trace: drop_spte+0x83/0xb0 [kvm] mmu_page_zap_pte+0xcc/0xe0 [kvm] kvm_mmu_prepare_zap_page+0x81/0x4a0 [kvm] kvm_mmu_invalidate_zap_all_pages+0x159/0x220 [kvm] kvm_arch_flush_shadow_all+0xe/0x10 [kvm] kvm_mmu_notifier_release+0x6c/0xa0 [kvm] ? kvm_mmu_notifier_release+0x5/0xa0 [kvm] __mmu_notifier_release+0x79/0x110 ? __mmu_notifier_release+0x5/0x110 exit_mmap+0x15a/0x170 ? do_exit+0x281/0xcb0 mmput+0x66/0x160 do_exit+0x2c9/0xcb0 ? __context_tracking_exit.part.5+0x4a/0x150 do_group_exit+0x50/0xd0 SyS_exit_group+0x14/0x20 do_syscall_64+0x73/0x1f0 entry_SYSCALL64_slow_path+0x25/0x25 The reason is that when creates new memslot, there is no guarantee for new memslot not overlap with private memslots. This can be triggered by the following program: #include <fcntl.h> #include <pthread.h> #include <setjmp.h> #include <signal.h> #include <stddef.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/ioctl.h> #include <sys/stat.h> #include <sys/syscall.h> #include <sys/types.h> #include <unistd.h> #include <linux/kvm.h> long r[16]; int main() { void *p = valloc(0x4000); r[2] = open("/dev/kvm", 0); r[3] = ioctl(r[2], KVM_CREATE_VM, 0x0ul); uint64_t addr = 0xf000; ioctl(r[3], KVM_SET_IDENTITY_MAP_ADDR, &addr); r[6] = ioctl(r[3], KVM_CREATE_VCPU, 0x0ul); ioctl(r[3], KVM_SET_TSS_ADDR, 0x0ul); ioctl(r[6], KVM_RUN, 0); ioctl(r[6], KVM_RUN, 0); struct kvm_userspace_memory_region mr = { .slot = 0, .flags = KVM_MEM_LOG_DIRTY_PAGES, .guest_phys_addr = 0xf000, .memory_size = 0x4000, .userspace_addr = (uintptr_t) p }; ioctl(r[3], KVM_SET_USER_MEMORY_REGION, &mr); return 0; } This patch fixes the bug by not adding a new memslot even if it overlaps with private memslots. Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
2017-12-25kvm, mm: account kvm related kmem slabs to kmemcgShakeel Butt1-1/+1
[ Upstream commit 46bea48ac241fe0b413805952dda74dd0c09ba8b ] The kvm slabs can consume a significant amount of system memory and indeed in our production environment we have observed that a lot of machines are spending significant amount of memory that can not be left as system memory overhead. Also the allocations from these slabs can be triggered directly by user space applications which has access to kvm and thus a buggy application can leak such memory. So, these caches should be accounted to kmemcg. Signed-off-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-25KVM: pci-assign: do not map smm memory slot pages in vt-d page tablesHerongguang (Stephen)1-1/+1
[ Upstream commit 0292e169b2d9c8377a168778f0b16eadb1f578fd ] or VM memory are not put thus leaked in kvm_iommu_unmap_memslots() when destroy VM. This is consistent with current vfio implementation. Signed-off-by: herongguang <herongguang.he@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-16KVM: arm/arm64: vgic-its: Preserve the revious read from the pending tableMarc Zyngier1-1/+1
commit 64afe6e9eb4841f35317da4393de21a047a883b3 upstream. The current pending table parsing code assumes that we keep the previous read of the pending bits, but keep that variable in the current block, making sure it is discarded on each loop. We end-up using whatever is on the stack. Who knows, it might just be the right thing... Fixes: 33d3bc9556a7d ("KVM: arm64: vgic-its: Read initial LPI pending table") Cc: stable@vger.kernel.org # 4.8 Reported-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-14KVM: arm/arm64: VGIC: Fix command handling while ITS being disabledAndre Przywara1-44/+65
[ Upstream commit a5e1e6ca94a8cec51571fd62e3eaec269717969c ] The ITS spec says that ITS commands are only processed when the ITS is enabled (section 8.19.4, Enabled, bit[0]). Our emulation was not taking this into account. Fix this by checking the enabled state before handling CWRITER writes. On the other hand that means that CWRITER could advance while the ITS is disabled, and enabling it would need those commands to be processed. Fix this case as well by refactoring actual command processing and calling this from both the GITS_CWRITER and GITS_CTLR handlers. Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Christoffer Dall <cdall@linaro.org> Signed-off-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-14KVM: arm/arm64: vgic-its: Check result of allocation before useMarc Zyngier1-0/+2
commit 686f294f2f1ae40705283dd413ca1e4c14f20f93 upstream. We miss a test against NULL after allocation. Fixes: 6d03a68f8054 ("KVM: arm64: vgic-its: Turn device_id validation into generic ID validation") Reported-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Acked-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-14KVM: arm/arm64: vgic-irqfd: Fix MSI entry allocationMarc Zyngier1-2/+1
commit 150009e2c70cc3c6e97f00e7595055765d32fb85 upstream. Using the size of the structure we're allocating is a good idea and avoids any surprise... In this case, we're happilly confusing kvm_kernel_irq_routing_entry and kvm_irq_routing_entry... Fixes: 95b110ab9a09 ("KVM: arm/arm64: Enable irqchip routing") Reported-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-14KVM: arm/arm64: Fix broken GICH_ELRSR big endian conversionChristoffer Dall1-4/+0
commit fc396e066318c0a02208c1d3f0b62950a7714999 upstream. We are incorrectly rearranging 32-bit words inside a 64-bit typed value for big endian systems, which would result in never marking a virtual interrupt as inactive on big endian systems (assuming 32 or fewer LRs on the hardware). Fix this by not doing any word order manipulation for the typed values. Acked-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-14KVM: x86: fix APIC page invalidationRadim Krčmář1-0/+8
commit b1394e745b9453dcb5b0671c205b770e87dedb87 upstream. Implementation of the unpinned APIC page didn't update the VMCS address cache when invalidation was done through range mmu notifiers. This became a problem when the page notifier was removed. Re-introduce the arch-specific helper and call it from ...range_start. Reported-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> Fixes: 38b9917350cb ("kvm: vmx: Implement set_apic_access_page_addr") Fixes: 369ea8242c0f ("mm/rmap: update to new mmu_notifier semantic v2") Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Wanpeng Li <wanpeng.li@hotmail.com> Tested-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-09KVM: arm/arm64: Fix occasional warning from the timer work functionChristoffer Dall1-3/+0
[ Upstream commit 63e41226afc3f7a044b70325566fa86ac3142538 ] When a VCPU blocks (WFI) and has programmed the vtimer, we program a soft timer to expire in the future to wake up the vcpu thread when appropriate. Because such as wake up involves a vcpu kick, and the timer expire function can get called from interrupt context, and the kick may sleep, we have to schedule the kick in the work function. The work function currently has a warning that gets raised if it turns out that the timer shouldn't fire when it's run, which was added because the idea was that in that case the work should never have been cancelled. However, it turns out that this whole thing is racy and we can get spurious warnings. The problem is that we clear the armed flag in the work function, which may run in parallel with the kvm_timer_unschedule->timer_disarm() call. This results in a possible situation where the timer_disarm() call does not call cancel_work_sync(), which effectively synchronizes the completion of the work function with running the VCPU. As a result, the VCPU thread proceeds before the work function completees, causing changes to the timer state such that kvm_timer_should_fire(vcpu) returns false in the work function. All we do in the work function is to kick the VCPU, and an occasional rare extra kick never harmed anyone. Since the race above is extremely rare, we don't bother checking if the race happens but simply remove the check and the clearing of the armed flag from the work function. Reported-by: Matthias Brugger <mbrugger@suse.com> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-07-27vfio: New external user group/file matchAlex Williamson1-8/+19
commit 5d6dee80a1e94cc284d03e06d930e60e8d3ecf7d upstream. At the point where the kvm-vfio pseudo device wants to release its vfio group reference, we can't always acquire a new reference to make that happen. The group can be in a state where we wouldn't allow a new reference to be added. This new helper function allows a caller to match a file to a group to facilitate this. Given a file and group, report if they match. Thus the caller needs to already have a group reference to match to the file. This allows the deletion of a group without acquiring a new reference. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Tested-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-14KVM: arm/arm64: vgic-v2: Do not use Active+Pending state for a HW interruptMarc Zyngier1-0/+7
commit ddf42d068f8802de122bb7efdfcb3179336053f1 upstream. When an interrupt is injected with the HW bit set (indicating that deactivation should be propagated to the physical distributor), special care must be taken so that we never mark the corresponding LR with the Active+Pending state (as the pending state is kept in the physycal distributor). Cc: stable@vger.kernel.org Fixes: 140b086dd197 ("KVM: arm/arm64: vgic-new: Add GICv2 world switch backend") Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Christoffer Dall <cdall@linaro.org> Signed-off-by: Christoffer Dall <cdall@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-14KVM: arm/arm64: vgic-v3: Do not use Active+Pending state for a HW interruptMarc Zyngier1-0/+7
commit 3d6e77ad1489650afa20da92bb589c8778baa8da upstream. When an interrupt is injected with the HW bit set (indicating that deactivation should be propagated to the physical distributor), special care must be taken so that we never mark the corresponding LR with the Active+Pending state (as the pending state is kept in the physycal distributor). Fixes: 59529f69f504 ("KVM: arm/arm64: vgic-new: Add GICv3 world switch backend") Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Christoffer Dall <cdall@linaro.org> Signed-off-by: Christoffer Dall <cdall@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-04-08KVM: kvm_io_bus_unregister_dev() should never failDavid Hildenbrand2-18/+27
commit 90db10434b163e46da413d34db8d0e77404cc645 upstream. No caller currently checks the return value of kvm_io_bus_unregister_dev(). This is evil, as all callers silently go on freeing their device. A stale reference will remain in the io_bus, getting at least used again, when the iobus gets teared down on kvm_destroy_vm() - leading to use after free errors. There is nothing the callers could do, except retrying over and over again. So let's simply remove the bus altogether, print an error and make sure no one can access this broken bus again (returning -ENOMEM on any attempt to access it). Fixes: e93f8a0f821e ("KVM: convert io_bus to SRCU") Reported-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-04-08KVM: x86: clear bus pointer when destroyedPeter Xu1-1/+11
commit df630b8c1e851b5e265dc2ca9c87222e342c093b upstream. When releasing the bus, let's clear the bus pointers to mark it out. If any further device unregister happens on this bus, we know that we're done if we found the bus being released already. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Radim Krčmá