linux.git/virt, branch v4.14.161

KVM: arm/arm64: vgic: Don't rely on the wrong pending table

2019-12-17T19:38:51+00:00

commit ca185b260951d3b55108c0b95e188682d8a507b7 upstream.

It's possible that two LPIs locate in the same "byte_offset" but target
two different vcpus, where their pending status are indicated by two
different pending tables.  In such a scenario, using last_byte_offset
optimization will lead KVM relying on the wrong pending table entry.
Let us use last_ptr instead, which can be treated as a byte index into
a pending table and also, can be vcpu specific.

Fixes: 280771252c1b ("KVM: arm64: vgic-v3: KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES")
Cc: stable@vger.kernel.org
Signed-off-by: Zenghui Yu 
Signed-off-by: Marc Zyngier 
Acked-by: Eric Auger 
Link: https://lore.kernel.org/r/20191029071919.177-4-yuzenghui@huawei.com
Signed-off-by: Greg Kroah-Hartman

kvm: properly check debugfs dentry before using it

2019-12-05T14:37:59+00:00

[ Upstream commit 8ed0579c12b2fe56a1fac2f712f58fc26c1dc49b ]

debugfs can now report an error code if something went wrong instead of
just NULL.  So if the return value is to be used as a "real" dentry, it
needs to be checked if it is an error before dereferencing it.

This is now happening because of ff9fb72bc077 ("debugfs: return error
values, not NULL").  syzbot has found a way to trigger multiple debugfs
files attempting to be created, which fails, and then the error code
gets passed to dentry_path_raw() which obviously does not like it.

Reported-by: Eric Biggers 
Reported-and-tested-by: syzbot+7857962b4d45e602b8ad@syzkaller.appspotmail.com
Cc: "Radim Krčmář" 
Cc: kvm@vger.kernel.org
Acked-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved

2019-12-01T08:14:15+00:00

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 
Analyzed-by: David Hildenbrand 
Acked-by: Dan Williams 
Cc: stable@vger.kernel.org
Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings")
Signed-off-by: Sean Christopherson 
Signed-off-by: Paolo Bonzini 
[sean: backport to 4.x; resolve conflict in mmu.c]
Signed-off-by: Sean Christopherson 
Signed-off-by: Greg Kroah-Hartman

kvm: arm/arm64: Fix stage2_flush_memslot for 4 level page table

2019-11-24T07:22:53+00:00

[ Upstream commit d2db7773ba864df6b4e19643dfc54838550d8049 ]

So far we have only supported 3 level page table with fixed IPA of
40bits, where PUD is folded. With 4 level page tables, we need
to check if the PUD entry is valid or not. Fix stage2_flush_memslot()
to do this check, before walking down the table.

Acked-by: Christoffer Dall 
Acked-by: Marc Zyngier 
Reviewed-by: Eric Auger 
Signed-off-by: Suzuki K Poulose 
Signed-off-by: Marc Zyngier 
Signed-off-by: Sasha Levin

kvm: x86: mmu: Recovery of shattered NX large pages

2019-11-12T18:19:08+00:00

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 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

kvm: Add helper function for creating VM worker threads

2019-11-12T18:19:08+00:00

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 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

kvm: Convert kvm_lock to a mutex

2019-11-12T18:19:05+00:00

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 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

kvm: x86, powerpc: do not allow clearing largepages debugfs entry

2019-11-12T18:19:05+00:00

commit 833b45de69a6016c4b0cebe6765d526a31a81580 upstream.

The largepages debugfs entry is incremented/decremented as shadow
pages are created or destroyed.  Clearing it will result in an
underflow, which is harmless to KVM but ugly (and could be
misinterpreted by tools that use debugfs information), so make
this particular statistic read-only.

Signed-off-by: Paolo Bonzini 
Signed-off-by: Thomas Gleixner 
Cc: kvm-ppc@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

KVM: coalesced_mmio: add bounds checking

2019-09-21T05:15:28+00:00

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 
Signed-off-by: Jim Mattson 
Reported-by: syzbot+983c866c3dd6efa3662a@syzkaller.appspotmail.com
[Use READ_ONCE. - Paolo]
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

KVM: arm/arm64: Only skip MMIO insn once

2019-09-10T09:32:18+00:00

[ Upstream commit 2113c5f62b7423e4a72b890bd479704aa85c81ba ]

If after an MMIO exit to userspace a VCPU is immediately run with an
immediate_exit request, such as when a signal is delivered or an MMIO
emulation completion is needed, then the VCPU completes the MMIO
emulation and immediately returns to userspace. As the exit_reason
does not get changed from KVM_EXIT_MMIO in these cases we have to
be careful not to complete the MMIO emulation again, when the VCPU is
eventually run again, because the emulation does an instruction skip
(and doing too many skips would be a waste of guest code :-) We need
to use additional VCPU state to track if the emulation is complete.
As luck would have it, we already have 'mmio_needed', which even
appears to be used in this way by other architectures already.

Fixes: 0d640732dbeb ("arm64: KVM: Skip MMIO insn after emulation")
Acked-by: Mark Rutland 
Signed-off-by: Andrew Jones 
Signed-off-by: Marc Zyngier 
Signed-off-by: Sasha Levin