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 v4 9/9] KVM: x86: drop superfluous mmu_check_root() from fast_pgd_switch()
Date: Fri, 10 Jul 2020 16:11:57 +0200 [thread overview]
Message-ID: <20200710141157.1640173-10-vkuznets@redhat.com> (raw)
In-Reply-To: <20200710141157.1640173-1-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 13ec3c30eda2..50a923696bf1 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
next prev parent reply other threads:[~2020-07-10 14:12 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 14:11 [PATCH v4 0/9] KVM: nSVM: fixes for CR3/MMU switch upon nested guest entry/exit Vitaly Kuznetsov
2020-07-10 14:11 ` [PATCH v4 1/9] KVM: nSVM: split kvm_init_shadow_npt_mmu() from kvm_init_shadow_mmu() Vitaly Kuznetsov
2020-07-10 14:11 ` [PATCH v4 2/9] KVM: MMU: stop dereferencing vcpu->arch.mmu to get the context for MMU init Vitaly Kuznetsov
2020-07-10 14:11 ` [PATCH v4 3/9] KVM: nSVM: reset nested_run_pending upon nested_svm_vmrun_msrpm() failure Vitaly Kuznetsov
2020-07-10 14:11 ` [PATCH v4 4/9] KVM: nSVM: prepare to handle errors from enter_svm_guest_mode() Vitaly Kuznetsov
2020-07-10 14:11 ` [PATCH v4 5/9] KVM: nSVM: introduce nested_svm_load_cr3()/nested_npt_enabled() Vitaly Kuznetsov
2020-07-13 22:38 ` Sean Christopherson
2020-07-14 11:26 ` Vitaly Kuznetsov
2020-07-15 4:36 ` Sean Christopherson
2020-07-10 14:11 ` [PATCH v4 6/9] KVM: nSVM: move kvm_set_cr3() after nested_svm_uninit_mmu_context() Vitaly Kuznetsov
2020-07-10 14:11 ` [PATCH v4 7/9] KVM: nSVM: implement nested_svm_load_cr3() and use it for host->guest switch Vitaly Kuznetsov
2020-07-10 14:11 ` [PATCH v4 8/9] KVM: nSVM: use nested_svm_load_cr3() on guest->host switch Vitaly Kuznetsov
2020-07-10 14:11 ` Vitaly Kuznetsov [this message]
2020-07-10 17:03 ` [PATCH v4 0/9] KVM: nSVM: fixes for CR3/MMU switch upon nested guest entry/exit Paolo Bonzini
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200710141157.1640173-10-vkuznets@redhat.com \
--to=vkuznets@redhat.com \
--cc=jmattson@google.com \
--cc=junaids@google.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=sean.j.christopherson@intel.com \
--cc=wanpengli@tencent.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).