[PATCH v3 9/9] KVM: x86: drop superfluous mmu_check_root() from fast_pgd_switch()

[Vitaly Kuznetsov]

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@xxxxxxxxxx>
---
 arch/x86/kvm/mmu/mmu.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 1c3a231f825b..c004ef9caf8f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4277,8 +4277,7 @@ 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;
 }
-- 
2.25.4