diff options
| author |  Sean Christopherson <seanjc@google.com>
| 2021-06-22 00:24:54 -0700 |
|---|---|---|
| committer |  Paolo Bonzini <pbonzini@redhat.com>
| 2021-06-24 11:47:56 -0400 |
| commit | 6c6e166b2c8513721d166c74060d26d3f4aecb48 (patch) | |
| tree | bd2b8fc0fb6f6cbd2f7dc5589b52c7e087127982 /arch | |
| parent | KVM: sefltests: Add x86-64 test to verify MMU reacts to CPUID updates (diff) | |
| download | linux-6c6e166b2c8513721d166c74060d26d3f4aecb48.tar.gz linux-6c6e166b2c8513721d166c74060d26d3f4aecb48.tar.bz2 linux-6c6e166b2c8513721d166c74060d26d3f4aecb48.zip | |
KVM: x86/mmu: Don't WARN on a NULL shadow page in TDP MMU check
Treat a NULL shadow page in the "is a TDP MMU" check as valid, non-TDP
root. KVM uses a "direct" PAE paging MMU when TDP is disabled and the
guest is running with paging disabled. In that case, root_hpa points at
the pae_root page (of which only 32 bytes are used), not a standard
shadow page, and the WARN fires (a lot).
Fixes: 0b873fd7fb53 ("KVM: x86/mmu: Remove redundant is_tdp_mmu_enabled check")
Cc: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210622072454.3449146-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.h | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index b981a044ab55..1cae4485b3bc 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -94,11 +94,13 @@ static inline bool is_tdp_mmu(struct kvm_mmu *mmu) if (WARN_ON(!VALID_PAGE(hpa))) return false; + /* + * A NULL shadow page is legal when shadowing a non-paging guest with + * PAE paging, as the MMU will be direct with root_hpa pointing at the + * pae_root page, not a shadow page. + */ sp = to_shadow_page(hpa); - if (WARN_ON(!sp)) - return false; - - return is_tdp_mmu_page(sp) && sp->root_count; + return sp && is_tdp_mmu_page(sp) && sp->root_count; } #else static inline bool kvm_mmu_init_tdp_mmu(struct kvm *kvm) { return false; } |