From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 05/10] KVM: VMX: Invalidate hv_tlb_eptp to denote an EPTP mismatch
Date: Wed, 21 Oct 2020 14:39:20 +0200 [thread overview]
Message-ID: <87wnzj4utj.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20201020215613.8972-6-sean.j.christopherson@intel.com>
Sean Christopherson <sean.j.christopherson@intel.com> writes:
> Drop the dedicated 'ept_pointers_match' field in favor of stuffing
> 'hv_tlb_eptp' with INVALID_PAGE to mark it as invalid, i.e. to denote
> that there is at least one EPTP mismatch. Use a local variable to
> track whether or not a mismatch is detected so that hv_tlb_eptp can be
> used to skip redundant flushes.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 16 ++++++++--------
> arch/x86/kvm/vmx/vmx.h | 7 -------
> 2 files changed, 8 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 52cb9eec1db3..4dfde8b64750 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -498,13 +498,13 @@ static int hv_remote_flush_tlb_with_range(struct kvm *kvm,
> struct kvm_vmx *kvm_vmx = to_kvm_vmx(kvm);
> struct kvm_vcpu *vcpu;
> int ret = 0, i;
> + bool mismatch;
> u64 tmp_eptp;
>
> spin_lock(&kvm_vmx->ept_pointer_lock);
>
> - if (kvm_vmx->ept_pointers_match != EPT_POINTERS_MATCH) {
> - kvm_vmx->ept_pointers_match = EPT_POINTERS_MATCH;
> - kvm_vmx->hv_tlb_eptp = INVALID_PAGE;
> + if (!VALID_PAGE(kvm_vmx->hv_tlb_eptp)) {
> + mismatch = false;
>
> kvm_for_each_vcpu(i, vcpu, kvm) {
> tmp_eptp = to_vmx(vcpu)->ept_pointer;
> @@ -515,12 +515,13 @@ static int hv_remote_flush_tlb_with_range(struct kvm *kvm,
> if (!VALID_PAGE(kvm_vmx->hv_tlb_eptp))
> kvm_vmx->hv_tlb_eptp = tmp_eptp;
> else
> - kvm_vmx->ept_pointers_match
> - = EPT_POINTERS_MISMATCH;
> + mismatch = true;
>
> ret |= hv_remote_flush_eptp(tmp_eptp, range);
> }
> - } else if (VALID_PAGE(kvm_vmx->hv_tlb_eptp)) {
> + if (mismatch)
> + kvm_vmx->hv_tlb_eptp = INVALID_PAGE;
> + } else {
> ret = hv_remote_flush_eptp(kvm_vmx->hv_tlb_eptp, range);
> }
Personally, I find double negations like 'mismatch = false' hard to read
:-). What if we write this all like
if (!VALID_PAGE(kvm_vmx->hv_tlb_eptp)) {
kvm_vmx->hv_tlb_eptp = to_vmx(vcpu0)->ept_pointer;
kvm_for_each_vcpu() {
tmp_eptp = to_vmx(vcpu)->ept_pointer;
if (!VALID_PAGE(tmp_eptp) || tmp_eptp != kvm_vmx->hv_tlb_eptp)
kvm_vmx->hv_tlb_eptp = INVALID_PAGE;
if (VALID_PAGE(tmp_eptp))
ret |= hv_remote_flush_eptp(tmp_eptp, range);
}
} else {
ret = hv_remote_flush_eptp(kvm_vmx->hv_tlb_eptp, range);
}
(not tested and I've probably missed something)
>
> @@ -3042,8 +3043,7 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, unsigned long pgd,
> if (kvm_x86_ops.tlb_remote_flush) {
> spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock);
> to_vmx(vcpu)->ept_pointer = eptp;
> - to_kvm_vmx(kvm)->ept_pointers_match
> - = EPT_POINTERS_CHECK;
> + to_kvm_vmx(kvm)->hv_tlb_eptp = INVALID_PAGE;
> spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock);
> }
>
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index 3d557a065c01..e8d7d07b2020 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -288,12 +288,6 @@ struct vcpu_vmx {
> } shadow_msr_intercept;
> };
>
> -enum ept_pointers_status {
> - EPT_POINTERS_CHECK = 0,
> - EPT_POINTERS_MATCH = 1,
> - EPT_POINTERS_MISMATCH = 2
> -};
> -
> struct kvm_vmx {
> struct kvm kvm;
>
> @@ -302,7 +296,6 @@ struct kvm_vmx {
> gpa_t ept_identity_map_addr;
>
> hpa_t hv_tlb_eptp;
> - enum ept_pointers_status ept_pointers_match;
> spinlock_t ept_pointer_lock;
> };
--
Vitaly
next prev parent reply other threads:[~2020-10-21 12:39 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 21:56 [PATCH v2 00/10] KVM: VMX: Clean up Hyper-V PV TLB flush Sean Christopherson
2020-10-20 21:56 ` [PATCH v2 01/10] KVM: VMX: Track common EPTP for Hyper-V's paravirt " Sean Christopherson
2020-10-21 11:57 ` Vitaly Kuznetsov
2020-10-20 21:56 ` [PATCH v2 02/10] KVM: VMX: Stash kvm_vmx in a local variable for Hyper-V " Sean Christopherson
2020-10-21 12:00 ` Vitaly Kuznetsov
2020-10-20 21:56 ` [PATCH v2 03/10] KVM: VMX: Fold Hyper-V EPTP checking into it's only caller Sean Christopherson
2020-10-21 12:08 ` Vitaly Kuznetsov
2020-10-20 21:56 ` [PATCH v2 04/10] KVM: VMX: Do Hyper-V TLB flush iff vCPU's EPTP hasn't been flushed Sean Christopherson
2020-10-21 12:23 ` Vitaly Kuznetsov
2020-10-20 21:56 ` [PATCH v2 05/10] KVM: VMX: Invalidate hv_tlb_eptp to denote an EPTP mismatch Sean Christopherson
2020-10-21 12:39 ` Vitaly Kuznetsov [this message]
2020-10-21 16:38 ` Sean Christopherson
2020-10-22 9:03 ` Vitaly Kuznetsov
2020-10-20 21:56 ` [PATCH v2 06/10] KVM: VMX: Don't invalidate hv_tlb_eptp if the new EPTP matches Sean Christopherson
2020-10-21 13:47 ` Vitaly Kuznetsov
2020-10-20 21:56 ` [PATCH v2 07/10] KVM: VMX: Explicitly check for hv_remote_flush_tlb when loading pgd Sean Christopherson
[not found] ` <87r1pr4q8z.fsf@vitty.brq.redhat.com>
2020-10-21 17:30 ` Sean Christopherson
2020-10-20 21:56 ` [PATCH v2 08/10] KVM: VMX: Define Hyper-V paravirt TLB flush fields iff Hyper-V is enabled Sean Christopherson
2020-10-21 14:20 ` Vitaly Kuznetsov
2020-10-20 21:56 ` [PATCH v2 09/10] KVM: VMX: Skip additional Hyper-V TLB EPTP flushes if one fails Sean Christopherson
2020-10-21 14:22 ` Vitaly Kuznetsov
2020-10-20 21:56 ` [PATCH v2 10/10] KVM: VMX: Track PGD instead of EPTP for paravirt Hyper-V TLB flush Sean Christopherson
[not found] ` <87imb34p9b.fsf@vitty.brq.redhat.com>
2020-10-21 17:59 ` Sean Christopherson
2020-10-21 9:18 ` [PATCH v2 00/10] KVM: VMX: Clean up Hyper-V PV " Vitaly Kuznetsov
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=87wnzj4utj.fsf@vitty.brq.redhat.com \
--to=vkuznets@redhat.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--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).