All of lore.kernel.org
 help / color / mirror / Atom feed
From: Maxim Levitsky <mlevitsk@redhat.com>
To: kvm@vger.kernel.org
Cc: Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	linux-kernel@vger.kernel.org (open list:X86 ARCHITECTURE (32-BIT
	AND 64-BIT)),
	x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	Ingo Molnar <mingo@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Maxim Levitsky <mlevitsk@redhat.com>
Subject: [PATCH 8/8] KVM: nSVM: read only changed fields of the nested guest data area
Date: Thu, 20 Aug 2020 12:13:27 +0300	[thread overview]
Message-ID: <20200820091327.197807-9-mlevitsk@redhat.com> (raw)
In-Reply-To: <20200820091327.197807-1-mlevitsk@redhat.com>

This allows us to only read fields that are marked as dirty by the nested
guest on vmentry.

I doubt that this has any perf impact but this way it is a bit closer
to real hardware.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 arch/x86/kvm/svm/nested.c | 58 +++++++++++++++++++++++++--------------
 arch/x86/kvm/svm/svm.c    |  2 +-
 arch/x86/kvm/svm/svm.h    |  5 ++++
 3 files changed, 44 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index acc4b26fcfcc..f3eef48caee6 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -266,40 +266,57 @@ static void load_nested_vmcb_control(struct vcpu_svm *svm,
 }
 
 static void load_nested_vmcb_save(struct vcpu_svm *svm,
-				  struct vmcb_save_area *save)
+				  struct vmcb_save_area *save,
+				  u32 clean)
 {
 	svm->nested.vmcb->save.rflags = save->rflags;
 	svm->nested.vmcb->save.rax    = save->rax;
 	svm->nested.vmcb->save.rsp    = save->rsp;
 	svm->nested.vmcb->save.rip    = save->rip;
 
-	svm->nested.vmcb->save.es  = save->es;
-	svm->nested.vmcb->save.cs  = save->cs;
-	svm->nested.vmcb->save.ss  = save->ss;
-	svm->nested.vmcb->save.ds  = save->ds;
-	svm->nested.vmcb->save.cpl = save->cpl;
+	if (is_dirty(clean, VMCB_SEG)) {
+		svm->nested.vmcb->save.es  = save->es;
+		svm->nested.vmcb->save.cs  = save->cs;
+		svm->nested.vmcb->save.ss  = save->ss;
+		svm->nested.vmcb->save.ds  = save->ds;
+		svm->nested.vmcb->save.cpl = save->cpl;
+	}
 
-	svm->nested.vmcb->save.gdtr = save->gdtr;
-	svm->nested.vmcb->save.idtr = save->idtr;
+	if (is_dirty(clean, VMCB_DT)) {
+		svm->nested.vmcb->save.gdtr = save->gdtr;
+		svm->nested.vmcb->save.idtr = save->idtr;
+	}
 
-	svm->nested.vmcb->save.efer = save->efer;
-	svm->nested.vmcb->save.cr3 = save->cr3;
-	svm->nested.vmcb->save.cr4 = save->cr4;
-	svm->nested.vmcb->save.cr0 = save->cr0;
+	if (is_dirty(clean, VMCB_CR)) {
+		svm->nested.vmcb->save.efer = save->efer;
+		svm->nested.vmcb->save.cr3 = save->cr3;
+		svm->nested.vmcb->save.cr4 = save->cr4;
+		svm->nested.vmcb->save.cr0 = save->cr0;
+	}
 
-	svm->nested.vmcb->save.cr2 = save->cr2;
+	if (is_dirty(clean, VMCB_CR2))
+		svm->nested.vmcb->save.cr2 = save->cr2;
 
-	svm->nested.vmcb->save.dr7 = save->dr7;
-	svm->nested.vmcb->save.dr6 = save->dr6;
+	if (is_dirty(clean, VMCB_DR)) {
+		svm->nested.vmcb->save.dr7 = save->dr7;
+		svm->nested.vmcb->save.dr6 = save->dr6;
+	}
 
-	svm->nested.vmcb->save.g_pat = save->g_pat;
+	if ((clean & VMCB_NPT) == 0)
+		svm->nested.vmcb->save.g_pat = save->g_pat;
 }
 
 void load_nested_vmcb(struct vcpu_svm *svm, struct vmcb *nested_vmcb, u64 vmcb_gpa)
 {
-	svm->nested.vmcb_gpa = vmcb_gpa;
+	u32 clean = nested_vmcb->control.clean;
+
+	if (svm->nested.vmcb_gpa != vmcb_gpa) {
+		svm->nested.vmcb_gpa = vmcb_gpa;
+		clean = 0;
+	}
+
 	load_nested_vmcb_control(svm, &nested_vmcb->control);
-	load_nested_vmcb_save(svm, &nested_vmcb->save);
+	load_nested_vmcb_save(svm, &nested_vmcb->save, clean);
 }
 
 /*
@@ -619,7 +636,6 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 
 	/* Exit Guest-Mode */
 	leave_guest_mode(&svm->vcpu);
-	svm->nested.vmcb_gpa = 0;
 	WARN_ON_ONCE(svm->nested.nested_run_pending);
 
 	/* in case we halted in L2 */
@@ -676,7 +692,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	 * Note: since CPU might have changed the values we can't
 	 * trust clean bits
 	 */
-	load_nested_vmcb_save(svm, &nested_vmcb->save);
+	load_nested_vmcb_save(svm, &nested_vmcb->save, 0);
 
 	/* Restore the original control entries */
 	copy_vmcb_control_area(&vmcb->control, &hsave->control);
@@ -759,6 +775,7 @@ int svm_allocate_nested(struct vcpu_svm *svm)
 		goto free_page3;
 
 	svm->nested.vmcb = page_address(vmcb_page);
+	svm->nested.vmcb_gpa = U64_MAX;
 	clear_page(svm->nested.vmcb);
 
 	svm->nested.initialized = true;
@@ -785,6 +802,7 @@ void svm_free_nested(struct vcpu_svm *svm)
 
 	__free_page(virt_to_page(svm->nested.vmcb));
 	svm->nested.vmcb = NULL;
+	svm->nested.vmcb_gpa = U64_MAX;
 
 	svm->nested.initialized = false;
 }
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 06668e0f93e7..f0bb7f622dca 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3924,7 +3924,7 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
 		if (kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(vmcb_gpa), &map) == -EINVAL)
 			return 1;
 
-		load_nested_vmcb(svm, map.hva, vmcb);
+		load_nested_vmcb(svm, map.hva, vmcb_gpa);
 		ret = enter_svm_guest_mode(svm);
 
 		kvm_vcpu_unmap(&svm->vcpu, &map, true);
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 80231ef8de6f..4a383c519fdf 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -204,6 +204,11 @@ static inline void vmcb_mark_dirty(struct vmcb *vmcb, int bit)
 	vmcb->control.clean &= ~(1 << bit);
 }
 
+static inline bool is_dirty(u32 clean, int bit)
+{
+	return (clean & (1 << bit)) == 0;
+}
+
 static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
 {
 	return container_of(vcpu, struct vcpu_svm, vcpu);
-- 
2.26.2


  parent reply	other threads:[~2020-08-20  9:15 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-20  9:13 [PATCH 0/8] KVM: nSVM: ondemand nested state allocation + nested guest state caching Maxim Levitsky
2020-08-20  9:13 ` [PATCH 1/8] KVM: SVM: rename a variable in the svm_create_vcpu Maxim Levitsky
2020-08-20  9:13 ` [PATCH 2/8] KVM: nSVM: rename nested 'vmcb' to vmcb_gpa in few places Maxim Levitsky
2020-08-20  9:56   ` Paolo Bonzini
2020-08-20 10:00     ` Maxim Levitsky
2020-08-20 10:19       ` Paolo Bonzini
2020-08-20 10:23         ` Maxim Levitsky
2020-08-20 10:56           ` Paolo Bonzini
2020-08-20 11:52             ` Maxim Levitsky
2020-08-20  9:13 ` [PATCH 3/8] KVM: SVM: refactor msr permission bitmap allocation Maxim Levitsky
2020-08-20  9:13 ` [PATCH 4/8] KVM: x86: allow kvm_x86_ops.set_efer to return a value Maxim Levitsky
2020-08-25 22:47   ` kernel test robot
2020-08-20  9:13 ` [PATCH 5/8] KVM: nSVM: implement ondemand allocation of the nested state Maxim Levitsky
2020-08-20  9:58   ` Paolo Bonzini
2020-08-20 10:02     ` Maxim Levitsky
2020-08-20  9:13 ` [PATCH 6/8] SVM: nSVM: cache whole nested vmcb instead of only its control area Maxim Levitsky
2020-08-20  9:13 ` [PATCH 7/8] KVM: nSVM: implement caching of nested vmcb save area Maxim Levitsky
2020-08-20  9:13 ` Maxim Levitsky [this message]
2020-08-20  9:55   ` [PATCH 8/8] KVM: nSVM: read only changed fields of the nested guest data area Paolo Bonzini
2020-08-20  9:57     ` Maxim Levitsky
2020-08-20 10:01   ` Paolo Bonzini
2020-08-20 10:05     ` Maxim Levitsky
2020-08-20 10:18       ` Paolo Bonzini
2020-08-20 10:26         ` Maxim Levitsky

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=20200820091327.197807-9-mlevitsk@redhat.com \
    --to=mlevitsk@redhat.com \
    --cc=bp@alien8.de \
    --cc=hpa@zytor.com \
    --cc=jmattson@google.com \
    --cc=joro@8bytes.org \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=sean.j.christopherson@intel.com \
    --cc=tglx@linutronix.de \
    --cc=vkuznets@redhat.com \
    --cc=wanpengli@tencent.com \
    --cc=x86@kernel.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.