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| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2019-02-22 17:45:01 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-02-22 19:24:48 +0100 |
| commit | ad7dc69aeb23138cc23c406cac25003b97e8ee17 (patch) | |
| tree | d4f2fbec9ea5c23b6525488595705c588250a3bd /arch/x86/include/asm | |
| parent | 73de65f5b9de517d8d9251a755e91296dd521ca6 (diff) | |
| download | linux-0-day-ad7dc69aeb23138cc23c406cac25003b97e8ee17.tar.gz linux-0-day-ad7dc69aeb23138cc23c406cac25003b97e8ee17.tar.xz | |
x86/kvm/mmu: fix switch between root and guest MMUs
Commit 14c07ad89f4d ("x86/kvm/mmu: introduce guest_mmu") brought one subtle
change: previously, when switching back from L2 to L1, we were resetting
MMU hooks (like mmu->get_cr3()) in kvm_init_mmu() called from
nested_vmx_load_cr3() and now we do that in nested_ept_uninit_mmu_context()
when we re-target vcpu->arch.mmu pointer.
The change itself looks logical: if nested_ept_init_mmu_context() changes
something than nested_ept_uninit_mmu_context() restores it back. There is,
however, one thing: the following call chain:
nested_vmx_load_cr3()
kvm_mmu_new_cr3()
__kvm_mmu_new_cr3()
fast_cr3_switch()
cached_root_available()
now happens with MMU hooks pointing to the new MMU (root MMU in our case)
while previously it was happening with the old one. cached_root_available()
tries to stash current root but it is incorrect to read current CR3 with
mmu->get_cr3(), we need to use old_mmu->get_cr3() which in case we're
switching from L2 to L1 is guest_mmu. (BTW, in shadow page tables case this
is a non-issue because we don't switch MMU).
While we could've tried to guess that we're switching between MMUs and call
the right ->get_cr3() from cached_root_available() this seems to be overly
complicated. Instead, just stash the corresponding CR3 when setting
root_hpa and make cached_root_available() use the stashed value.
Fixes: 14c07ad89f4d ("x86/kvm/mmu: introduce guest_mmu")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/include/asm')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 4660ce90de7ff..593e17b7797e2 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -397,6 +397,7 @@ struct kvm_mmu { void (*update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *spte, const void *pte); hpa_t root_hpa; + gpa_t root_cr3; union kvm_mmu_role mmu_role; u8 root_level; u8 shadow_root_level; |