linux.git/arch/loongarch, branch master

LoongArch: KVM: Mark hrtimer to expire in hard interrupt context

2024-10-23T14:15:44+00:00

Like commit 2c0d278f3293f ("KVM: LAPIC: Mark hrtimer to expire in hard
interrupt context") and commit 9090825fa9974 ("KVM: arm/arm64: Let the
timer expire in hardirq context on RT"), On PREEMPT_RT enabled kernels
unmarked hrtimers are moved into soft interrupt expiry mode by default.
Then the timers are canceled from an preempt-notifier which is invoked
with disabled preemption which is not allowed on PREEMPT_RT.

The timer callback is short so in could be invoked in hard-IRQ context.
So let the timer expire on hard-IRQ context even on -RT.

This fix a "scheduling while atomic" bug for PREEMPT_RT enabled kernels:

 BUG: scheduling while atomic: qemu-system-loo/1011/0x00000002
 Modules linked in: amdgpu rfkill nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat ns
 CPU: 1 UID: 0 PID: 1011 Comm: qemu-system-loo Tainted: G        W          6.12.0-rc2+ #1774
 Tainted: [W]=WARN
 Hardware name: Loongson Loongson-3A5000-7A1000-1w-CRB/Loongson-LS3A5000-7A1000-1w-CRB, BIOS vUDK2018-LoongArch-V2.0.0-prebeta9 10/21/2022
 Stack : ffffffffffffffff 0000000000000000 9000000004e3ea38 9000000116744000
         90000001167475a0 0000000000000000 90000001167475a8 9000000005644830
         90000000058dc000 90000000058dbff8 9000000116747420 0000000000000001
         0000000000000001 6a613fc938313980 000000000790c000 90000001001c1140
         00000000000003fe 0000000000000001 000000000000000d 0000000000000003
         0000000000000030 00000000000003f3 000000000790c000 9000000116747830
         90000000057ef000 0000000000000000 9000000005644830 0000000000000004
         0000000000000000 90000000057f4b58 0000000000000001 9000000116747868
         900000000451b600 9000000005644830 9000000003a13998 0000000010000020
         00000000000000b0 0000000000000004 0000000000000000 0000000000071c1d
         ...
 Call Trace:
 [<9000000003a13998>] show_stack+0x38/0x180
 [<9000000004e3ea34>] dump_stack_lvl+0x84/0xc0
 [<9000000003a71708>] __schedule_bug+0x48/0x60
 [<9000000004e45734>] __schedule+0x1114/0x1660
 [<9000000004e46040>] schedule_rtlock+0x20/0x60
 [<9000000004e4e330>] rtlock_slowlock_locked+0x3f0/0x10a0
 [<9000000004e4f038>] rt_spin_lock+0x58/0x80
 [<9000000003b02d68>] hrtimer_cancel_wait_running+0x68/0xc0
 [<9000000003b02e30>] hrtimer_cancel+0x70/0x80
 [] kvm_restore_timer+0x50/0x1a0 [kvm]
 [] kvm_arch_vcpu_load+0x68/0x2a0 [kvm]
 [] kvm_sched_in+0x34/0x60 [kvm]
 [<9000000003a749a0>] finish_task_switch.isra.0+0x140/0x2e0
 [<9000000004e44a70>] __schedule+0x450/0x1660
 [<9000000004e45cb0>] schedule+0x30/0x180
 [] kvm_vcpu_block+0x70/0x120 [kvm]
 [] kvm_vcpu_halt+0x60/0x3e0 [kvm]
 [] kvm_handle_gspr+0x3f4/0x4e0 [kvm]
 [] kvm_handle_exit+0x1c8/0x260 [kvm]

Reviewed-by: Bibo Mao 
Signed-off-by: Huacai Chen

LoongArch: Make KASAN usable for variable cpu_vabits

2024-10-23T14:15:30+00:00

Currently, KASAN on LoongArch assume the CPU VA bits is 48, which is
true for Loongson-3 series, but not for Loongson-2 series (only 40 or
lower), this patch fix that issue and make KASAN usable for variable
cpu_vabits.

Solution is very simple: Just define XRANGE_SHADOW_SHIFT which means
valid address length from VA_BITS to min(cpu_vabits, VA_BITS).

Cc: stable@vger.kernel.org
Signed-off-by: Kanglong Wang 
Signed-off-by: Huacai Chen

LoongArch: Set initial pte entry with PAGE_GLOBAL for kernel space

2024-10-21T14:11:19+00:00

There are two pages in one TLB entry on LoongArch system. For kernel
space, it requires both two pte entries (buddies) with PAGE_GLOBAL bit
set, otherwise HW treats it as non-global tlb, there will be potential
problems if tlb entry for kernel space is not global. Such as fail to
flush kernel tlb with the function local_flush_tlb_kernel_range() which
supposed only flush tlb with global bit.

Kernel address space areas include percpu, vmalloc, vmemmap, fixmap and
kasan areas. For these areas both two consecutive page table entries
should be enabled with PAGE_GLOBAL bit. So with function set_pte() and
pte_clear(), pte buddy entry is checked and set besides its own pte
entry. However it is not atomic operation to set both two pte entries,
there is problem with test_vmalloc test case.

So function kernel_pte_init() is added to init a pte table when it is
created for kernel address space, and the default initial pte value is
PAGE_GLOBAL rather than zero at beginning. Then only its own pte entry
need update with function set_pte() and pte_clear(), nothing to do with
the pte buddy entry.

Signed-off-by: Bibo Mao 
Signed-off-by: Huacai Chen

LoongArch: Don't crash in stack_top() for tasks without vDSO

2024-10-21T14:11:19+00:00

Not all tasks have a vDSO mapped, for example kthreads never do. If such
a task ever ends up calling stack_top(), it will derefence the NULL vdso
pointer and crash.

This can for example happen when using kunit:

	[<9000000000203874>] stack_top+0x58/0xa8
	[<90000000002956cc>] arch_pick_mmap_layout+0x164/0x220
	[<90000000003c284c>] kunit_vm_mmap_init+0x108/0x12c
	[<90000000003c1fbc>] __kunit_add_resource+0x38/0x8c
	[<90000000003c2704>] kunit_vm_mmap+0x88/0xc8
	[<9000000000410b14>] usercopy_test_init+0xbc/0x25c
	[<90000000003c1db4>] kunit_try_run_case+0x5c/0x184
	[<90000000003c3d54>] kunit_generic_run_threadfn_adapter+0x24/0x48
	[<900000000022e4bc>] kthread+0xc8/0xd4
	[<9000000000200ce8>] ret_from_kernel_thread+0xc/0xa4

Fixes: 803b0fc5c3f2 ("LoongArch: Add process management")
Signed-off-by: Thomas Weißschuh 
Signed-off-by: Huacai Chen

LoongArch: Set correct size for vDSO code mapping

2024-10-21T14:11:19+00:00

The current size of vDSO code mapping is hardcoded to PAGE_SIZE. This
cannot work for 4KB page size after commit 18efd0b10e0fd77 ("LoongArch:
vDSO: Wire up getrandom() vDSO implementation") because the code size
increases to 8KB. Thus set the code mapping size to its real size, i.e.
PAGE_ALIGN(vdso_end - vdso_start).

Fixes: 18efd0b10e0fd77 ("LoongArch: vDSO: Wire up getrandom() vDSO implementation")
Reviewed-by: Xi Ruoyao 
Signed-off-by: Huacai Chen

LoongArch: Enable IRQ if do_ale() triggered in irq-enabled context

2024-10-21T14:11:19+00:00

Unaligned access exception can be triggered in irq-enabled context such
as user mode, in this case do_ale() may call get_user() which may cause
sleep. Then we will get:

 BUG: sleeping function called from invalid context at arch/loongarch/kernel/access-helper.h:7
 in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 129, name: modprobe
 preempt_count: 0, expected: 0
 RCU nest depth: 0, expected: 0
 CPU: 0 UID: 0 PID: 129 Comm: modprobe Tainted: G        W          6.12.0-rc1+ #1723
 Tainted: [W]=WARN
 Stack : 9000000105e0bd48 0000000000000000 9000000003803944 9000000105e08000
         9000000105e0bc70 9000000105e0bc78 0000000000000000 0000000000000000
         9000000105e0bc78 0000000000000001 9000000185e0ba07 9000000105e0b890
         ffffffffffffffff 9000000105e0bc78 73924b81763be05b 9000000100194500
         000000000000020c 000000000000000a 0000000000000000 0000000000000003
         00000000000023f0 00000000000e1401 00000000072f8000 0000007ffbb0e260
         0000000000000000 0000000000000000 9000000005437650 90000000055d5000
         0000000000000000 0000000000000003 0000007ffbb0e1f0 0000000000000000
         0000005567b00490 0000000000000000 9000000003803964 0000007ffbb0dfec
         00000000000000b0 0000000000000007 0000000000000003 0000000000071c1d
         ...
 Call Trace:
 [<9000000003803964>] show_stack+0x64/0x1a0
 [<9000000004c57464>] dump_stack_lvl+0x74/0xb0
 [<9000000003861ab4>] __might_resched+0x154/0x1a0
 [<900000000380c96c>] emulate_load_store_insn+0x6c/0xf60
 [<9000000004c58118>] do_ale+0x78/0x180
 [<9000000003801bc8>] handle_ale+0x128/0x1e0

So enable IRQ if unaligned access exception is triggered in irq-enabled
context to fix it.

Cc: stable@vger.kernel.org
Reported-by: Binbin Zhou 
Signed-off-by: Huacai Chen

LoongArch: Get correct cores_per_package for SMT systems

2024-10-21T14:11:18+00:00

In loongson_sysconf, The "core" of cores_per_node and cores_per_package
stands for a logical core, which means in a SMT system it stands for a
thread indeed. This information is gotten from SMBIOS Type4 Structure,
so in order to get a correct cores_per_package for both SMT and non-SMT
systems in parse_cpu_table() we should use SMBIOS_THREAD_PACKAGE_OFFSET
instead of SMBIOS_CORE_PACKAGE_OFFSET.

Cc: stable@vger.kernel.org
Reported-by: Chao Li 
Tested-by: Chao Li 
Signed-off-by: Huacai Chen

LoongArch: Use "Exception return address" to comment ERA

2024-10-21T14:11:18+00:00

The information contained in the comment for LOONGARCH_CSR_ERA is even
less informative than the macro itself, which can cause confusion for
junior developers. Let's use the full English term.

Signed-off-by: Yanteng Si 
Signed-off-by: Huacai Chen

move asm/unaligned.h to linux/unaligned.h

2024-10-02T21:23:23+00:00

asm/unaligned.h is always an include of asm-generic/unaligned.h;
might as well move that thing to linux/unaligned.h and include
that - there's nothing arch-specific in that header.

auto-generated by the following:

for i in `git grep -l -w asm/unaligned.h`; do
	sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i
done
for i in `git grep -l -w asm-generic/unaligned.h`; do
	sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i
done
git mv include/asm-generic/unaligned.h include/linux/unaligned.h
git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h
sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild
sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2024-09-28T16:20:14+00:00

Pull x86 kvm updates from Paolo Bonzini:
 "x86:

   - KVM currently invalidates the entirety of the page tables, not just
     those for the memslot being touched, when a memslot is moved or
     deleted.

     This does not traditionally have particularly noticeable overhead,
     but Intel's TDX will require the guest to re-accept private pages
     if they are dropped from the secure EPT, which is a non starter.

     Actually, the only reason why this is not already being done is a
     bug which was never fully investigated and caused VM instability
     with assigned GeForce GPUs, so allow userspace to opt into the new
     behavior.

   - Advertise AVX10.1 to userspace (effectively prep work for the
     "real" AVX10 functionality that is on the horizon)

   - Rework common MSR handling code to suppress errors on userspace
     accesses to unsupported-but-advertised MSRs

     This will allow removing (almost?) all of KVM's exemptions for
     userspace access to MSRs that shouldn't exist based on the vCPU
     model (the actual cleanup is non-trivial future work)

   - Rework KVM's handling of x2APIC ICR, again, because AMD (x2AVIC)
     splits the 64-bit value into the legacy ICR and ICR2 storage,
     whereas Intel (APICv) stores the entire 64-bit value at the ICR
     offset

   - Fix a bug where KVM would fail to exit to userspace if one was
     triggered by a fastpath exit handler

   - Add fastpath handling of HLT VM-Exit to expedite re-entering the
     guest when there's already a pending wake event at the time of the
     exit

   - Fix a WARN caused by RSM entering a nested guest from SMM with
     invalid guest state, by forcing the vCPU out of guest mode prior to
     signalling SHUTDOWN (the SHUTDOWN hits the VM altogether, not the
     nested guest)

   - Overhaul the "unprotect and retry" logic to more precisely identify
     cases where retrying is actually helpful, and to harden all retry
     paths against putting the guest into an infinite retry loop

   - Add support for yielding, e.g. to honor NEED_RESCHED, when zapping
     rmaps in the shadow MMU

   - Refactor pieces of the shadow MMU related to aging SPTEs in
     prepartion for adding multi generation LRU support in KVM

   - Don't stuff the RSB after VM-Exit when RETPOLINE=y and AutoIBRS is
     enabled, i.e. when the CPU has already flushed the RSB

   - Trace the per-CPU host save area as a VMCB pointer to improve
     readability and cleanup the retrieval of the SEV-ES host save area

   - Remove unnecessary accounting of temporary nested VMCB related
     allocations

   - Set FINAL/PAGE in the page fault error code for EPT violations if
     and only if the GVA is valid. If the GVA is NOT valid, there is no
     guest-side page table walk and so stuffing paging related metadata
     is nonsensical

   - Fix a bug where KVM would incorrectly synthesize a nested VM-Exit
     instead of emulating posted interrupt delivery to L2

   - Add a lockdep assertion to detect unsafe accesses of vmcs12
     structures

   - Harden eVMCS loading against an impossible NULL pointer deref
     (really truly should be impossible)

   - Minor SGX fix and a cleanup

   - Misc cleanups

  Generic:

   - Register KVM's cpuhp and syscore callbacks when enabling
     virtualization in hardware, as the sole purpose of said callbacks
     is to disable and re-enable virtualization as needed

   - Enable virtualization when KVM is loaded, not right before the
     first VM is created

     Together with the previous change, this simplifies a lot the logic
     of the callbacks, because their very existence implies
     virtualization is enabled

   - Fix a bug that results in KVM prematurely exiting to userspace for
     coalesced MMIO/PIO in many cases, clean up the related code, and
     add a testcase

   - Fix a bug in kvm_clear_guest() where it would trigger a buffer
     overflow _if_ the gpa+len crosses a page boundary, which thankfully
     is guaranteed to not happen in the current code base. Add WARNs in
     more helpers that read/write guest memory to detect similar bugs

  Selftests:

   - Fix a goof that caused some Hyper-V tests to be skipped when run on
     bare metal, i.e. NOT in a VM

   - Add a regression test for KVM's handling of SHUTDOWN for an SEV-ES
     guest

   - Explicitly include one-off assets in .gitignore. Past Sean was
     completely wrong about not being able to detect missing .gitignore
     entries

   - Verify userspace single-stepping works when KVM happens to handle a
     VM-Exit in its fastpath

   - Misc cleanups"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (127 commits)
  Documentation: KVM: fix warning in "make htmldocs"
  s390: Enable KVM_S390_UCONTROL config in debug_defconfig
  selftests: kvm: s390: Add VM run test case
  KVM: SVM: let alternatives handle the cases when RSB filling is required
  KVM: VMX: Set PFERR_GUEST_{FINAL,PAGE}_MASK if and only if the GVA is valid
  KVM: x86/mmu: Use KVM_PAGES_PER_HPAGE() instead of an open coded equivalent
  KVM: x86/mmu: Add KVM_RMAP_MANY to replace open coded '1' and '1ul' literals
  KVM: x86/mmu: Fold mmu_spte_age() into kvm_rmap_age_gfn_range()
  KVM: x86/mmu: Morph kvm_handle_gfn_range() into an aging specific helper
  KVM: x86/mmu: Honor NEED_RESCHED when zapping rmaps and blocking is allowed
  KVM: x86/mmu: Add a helper to walk and zap rmaps for a memslot
  KVM: x86/mmu: Plumb a @can_yield parameter into __walk_slot_rmaps()
  KVM: x86/mmu: Move walk_slot_rmaps() up near for_each_slot_rmap_range()
  KVM: x86/mmu: WARN on MMIO cache hit when emulating write-protected gfn
  KVM: x86/mmu: Detect if unprotect will do anything based on invalid_list
  KVM: x86/mmu: Subsume kvm_mmu_unprotect_page() into the and_retry() version
  KVM: x86: Rename reexecute_instruction()=>kvm_unprotect_and_retry_on_failure()
  KVM: x86: Update retry protection fields when forcing retry on emulation failure
  KVM: x86: Apply retry protection to "unprotect on failure" path
  KVM: x86: Check EMULTYPE_WRITE_PF_TO_SP before unprotecting gfn
  ...