From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Junaid Shahid <junaids@google.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH v2 3/3] KVM: x86: drop superfluous mmu_check_root() from fast_pgd_switch()
Date: Wed, 8 Jul 2020 11:36:11 +0200 [thread overview]
Message-ID: <20200708093611.1453618-4-vkuznets@redhat.com> (raw)
In-Reply-To: <20200708093611.1453618-1-vkuznets@redhat.com>
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>
---
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 ebf0cb3f1ce0..16c7701f1741 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
prev parent reply other threads:[~2020-07-08 9:36 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-08 9:36 [PATCH v2 0/3] KVM: nSVM: fix #TF from CR3 switch when entering guest Vitaly Kuznetsov
2020-07-08 9:36 ` [PATCH v2 1/3] KVM: nSVM: split kvm_init_shadow_npt_mmu() from kvm_init_shadow_mmu() Vitaly Kuznetsov
2020-07-08 11:25 ` Paolo Bonzini
2020-07-08 9:36 ` [PATCH v2 2/3] KVM: nSVM: properly call kvm_mmu_new_pgd() upon switching to guest Vitaly Kuznetsov
2020-07-08 11:49 ` Paolo Bonzini
2020-07-08 14:39 ` Vitaly Kuznetsov
2020-07-08 9:36 ` Vitaly Kuznetsov [this message]
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