Messages in this thread | | | Date | Thu, 3 Dec 2020 16:43:54 -0800 | From | Sean Christopherson <> | Subject | Re: [PATCH] kvm: x86/mmu: Use cpuid to determine max gfn |
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On Thu, Dec 03, 2020, Rick Edgecombe wrote: > In the TDP MMU, use shadow_phys_bits to dermine the maximum possible GFN > mapped in the guest for zapping operations. boot_cpu_data.x86_phys_bits > may be reduced in the case of HW features that steal HPA bits for other > purposes. However, this doesn't necessarily reduce GPA space that can be > accessed via TDP. So zap based on a maximum gfn calculated with MAXPHYADDR > retrieved from CPUID. This is already stored in shadow_phys_bits, so use > it instead of x86_phys_bits. > > Fixes: faaf05b00aec ("kvm: x86/mmu: Support zapping SPTEs in the TDP MMU") > Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Dang, in hindsight it'd be nice if KVM_CAP_SMALLER_MAXPHYADDR allowed explicitly setting the max MAXPHYADDR for an entire VM instead of being a simple toggle. E.g. TDX and SEV-ES likely could also make use of "what's this VM's max GPA?".
Reviewed-by: Sean Christopherson <seanjc@google.com>
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