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KVM: x86/mmu: Embed direct bits into gpa for KVM_PRE_FAULT_MEMORY

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Bug[*] reported for TDX case when enabling KVM_PRE_FAULT_MEMORY in QEMU.

It turns out that @gpa passed to kvm_mmu_do_page_fault() doesn't have
shared bit set when the memory attribute of it is shared, and it leads
to wrong root in tdp_mmu_get_root_for_fault().

Fix it by embedding the direct bits in the gpa that is passed to
kvm_tdp_map_page(), when the memory of the gpa is not private.

[*] https://lore.kernel.org/qemu-devel/4a757796-11c2-47f1-ae0d-335626e818fd@intel.com/

Reported-by: Xiaoyao Li <xiaoyao.li@intel.com>
Closes: https://lore.kernel.org/qemu-devel/4a757796-11c2-47f1-ae0d-335626e818fd@intel.com/
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-ID: <20250611001018.2179964-1-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2025-06-10 20:10:18 -04:00
parent 179a8427fc
commit aa2024c01a
1 changed files with 5 additions and 1 deletions
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6
arch/x86/kvm/mmu/mmu.c
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@ -4896,6 +4896,7 @@ long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu,
{
u64 error_code = PFERR_GUEST_FINAL_MASK;
u8 level = PG_LEVEL_4K;
u64 direct_bits;
u64 end;
int r;
@ -4910,15 +4911,18 @@ long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu,
if (r)
return r;
direct_bits = 0;
if (kvm_arch_has_private_mem(vcpu->kvm) &&
kvm_mem_is_private(vcpu->kvm, gpa_to_gfn(range->gpa)))
error_code |= PFERR_PRIVATE_ACCESS;
else
direct_bits = gfn_to_gpa(kvm_gfn_direct_bits(vcpu->kvm));
/*
* Shadow paging uses GVA for kvm page fault, so restrict to
* two-dimensional paging.
*/
r = kvm_tdp_map_page(vcpu, range->gpa, error_code, &level);
r = kvm_tdp_map_page(vcpu, range->gpa | direct_bits, error_code, &level);
if (r < 0)
return r;