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KVM: x86: drop superfluous mmu_check_root() from fast_pgd_switch() 

The mmu_check_root() check in fast_pgd_switch() seems to be
superfluous: when GPA is outside of the visible range
cached_root_available() will fail for non-direct roots
(as we can't have a matching one on the list) and we don't
seem to care for direct ones.

Also, raising #TF immediately when a non-existent GFN is written to CR3
doesn't seem to mach architectural behavior. Drop the check.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200710141157.1640173-10-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2020-07-10 16:11:57 +02:00 committed by Paolo Bonzini
parent d82aaef9c8
commit fe9304d318
1 changed files with 1 additions and 2 deletions
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3
arch/x86/kvm/mmu/mmu.c
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@ -4243,8 +4243,7 @@ static bool fast_pgd_switch(struct kvm_vcpu *vcpu, gpa_t new_pgd,
*/
if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL &&
mmu->root_level >= PT64_ROOT_4LEVEL)
return !mmu_check_root(vcpu, new_pgd >> PAGE_SHIFT) &&
cached_root_available(vcpu, new_pgd, new_role);
return cached_root_available(vcpu, new_pgd, new_role);
return false;
}