forked from rpms/kernel
88 lines
3.5 KiB
Diff
88 lines
3.5 KiB
Diff
From 6f404ab35a9a684cb6ee146a39413698bba17fe4 Mon Sep 17 00:00:00 2001
|
|
From: Nagappan Ramasamy Palaniappan <nagappan.ramasamy.palaniappan@oracle.com>
|
|
Date: Wed, 2 Aug 2023 12:50:36 +0000
|
|
Subject: [PATCH 1/5] KVM: x86/mmu: Fix race condition in direct_page_fault
|
|
|
|
make_mmu_pages_available() must be called with mmu_lock held for write.
|
|
However, if the TDP MMU is used, it will be called with mmu_lock held for
|
|
read.
|
|
This function does nothing unless shadow pages are used, so there is no
|
|
race unless nested TDP is used.
|
|
Since nested TDP uses shadow pages, old shadow pages may be zapped by this
|
|
function even when the TDP MMU is enabled.
|
|
Since shadow pages are never allocated by kvm_tdp_mmu_map(), a race
|
|
condition can be avoided by not calling make_mmu_pages_available() if the
|
|
TDP MMU is currently in use.
|
|
|
|
I encountered this when repeatedly starting and stopping nested VM.
|
|
It can be artificially caused by allocating a large number of nested TDP
|
|
SPTEs.
|
|
|
|
For example, the following BUG and general protection fault are caused in
|
|
the host kernel.
|
|
|
|
pte_list_remove: 00000000cd54fc10 many->many
|
|
------------[ cut here ]------------
|
|
kernel BUG at arch/x86/kvm/mmu/mmu.c:963!
|
|
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
|
|
RIP: 0010:pte_list_remove.cold+0x16/0x48 [kvm]
|
|
Call Trace:
|
|
<TASK>
|
|
drop_spte+0xe0/0x180 [kvm]
|
|
mmu_page_zap_pte+0x4f/0x140 [kvm]
|
|
__kvm_mmu_prepare_zap_page+0x62/0x3e0 [kvm]
|
|
kvm_mmu_zap_oldest_mmu_pages+0x7d/0xf0 [kvm]
|
|
direct_page_fault+0x3cb/0x9b0 [kvm]
|
|
kvm_tdp_page_fault+0x2c/0xa0 [kvm]
|
|
kvm_mmu_page_fault+0x207/0x930 [kvm]
|
|
npf_interception+0x47/0xb0 [kvm_amd]
|
|
svm_invoke_exit_handler+0x13c/0x1a0 [kvm_amd]
|
|
svm_handle_exit+0xfc/0x2c0 [kvm_amd]
|
|
kvm_arch_vcpu_ioctl_run+0xa79/0x1780 [kvm]
|
|
kvm_vcpu_ioctl+0x29b/0x6f0 [kvm]
|
|
__x64_sys_ioctl+0x95/0xd0
|
|
do_syscall_64+0x5c/0x90
|
|
|
|
general protection fault, probably for non-canonical address
|
|
0xdead000000000122: 0000 [#1] PREEMPT SMP NOPTI
|
|
RIP: 0010:kvm_mmu_commit_zap_page.part.0+0x4b/0xe0 [kvm]
|
|
Call Trace:
|
|
<TASK>
|
|
kvm_mmu_zap_oldest_mmu_pages+0xae/0xf0 [kvm]
|
|
direct_page_fault+0x3cb/0x9b0 [kvm]
|
|
kvm_tdp_page_fault+0x2c/0xa0 [kvm]
|
|
kvm_mmu_page_fault+0x207/0x930 [kvm]
|
|
npf_interception+0x47/0xb0 [kvm_amd]
|
|
|
|
CVE: CVE-2022-45869
|
|
Fixes: a2855afc7ee8 ("KVM: x86/mmu: Allow parallel page faults for the TDP MMU")
|
|
Signed-off-by: Kazuki Takiguchi <takiguchi.kazuki171@gmail.com>
|
|
Cc: stable@vger.kernel.org
|
|
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
|
|
|
|
Conflicts: dropped hunk in direct_page_fault because the following backported commits do the same thing
|
|
a158127f55b98c ("KVM: x86/mmu: Split out TDP MMU page fault handling")
|
|
1290f90e77186b ("KVM: x86/mmu: Stop needlessly making MMU pages available for TDP MMU faults")
|
|
|
|
Signed-off-by: Nagappan Ramasamy Palaniappan <nagappan.ramasamy.palaniappan@oracle.com>
|
|
Reviewed-by: Laurence Rochfort <laurence.rochfort@oracle.com>
|
|
---
|
|
arch/x86/kvm/mmu/mmu.c | 1 +
|
|
1 file changed, 1 insertion(+)
|
|
|
|
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
|
|
index 05c137831..2968f8137 100644
|
|
--- a/arch/x86/kvm/mmu/mmu.c
|
|
+++ b/arch/x86/kvm/mmu/mmu.c
|
|
@@ -2432,6 +2432,7 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm,
|
|
{
|
|
bool list_unstable, zapped_root = false;
|
|
|
|
+ lockdep_assert_held_write(&kvm->mmu_lock);
|
|
trace_kvm_mmu_prepare_zap_page(sp);
|
|
++kvm->stat.mmu_shadow_zapped;
|
|
*nr_zapped = mmu_zap_unsync_children(kvm, sp, invalid_list);
|
|
--
|
|
2.31.1
|
|
|