linux-kernel - [PATCH 11/11] KVM: SVM: Don't call instruction emulator for invd and wbinvd

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Date:	Fri, 19 Feb 2010 16:23:10 +0100
From:	Joerg Roedel <joerg.roedel@....com>
To:	Avi Kivity <avi@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com>
CC:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Joerg Roedel <joerg.roedel@....com>
Subject: [PATCH 11/11] KVM: SVM: Don't call instruction emulator for invd and wbinvd

There is an intercept for WBINVD and INVD in SVM so we don't
need the instruction emulator. The primary reason is that
the current instruction emulator fails to emulate these
instructions and the rip is not advanced.

Signed-off-by: Joerg Roedel <joerg.roedel@....com>
---
 arch/x86/kvm/emulate.c |    4 ++++
 arch/x86/kvm/svm.c     |   14 ++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 9beda8e..0180cb1 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1029,6 +1029,10 @@ done_prefixes:
 
 	/* Unrecognised? */
 	if (c->d == 0) {
+		/* Don't fail for invd and wbinvd*/
+		if (c->twobyte && (c->b == 0x08 || c->b == 0x09))
+			return 0;
+
 		DPRINTF("Cannot emulate %02x\n", c->b);
 		return -1;
 	}
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8119355..5fd00e8 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2117,6 +2117,16 @@ static int cpuid_interception(struct vcpu_svm *svm)
 	return 1;
 }
 
+static int invd_interception(struct vcpu_svm *svm)
+{
+	svm->next_rip = kvm_rip_read(&svm->vcpu) + 2;
+	skip_emulated_instruction(&svm->vcpu);
+
+	/* Nop */
+
+	return 1;
+}
+
 static int iret_interception(struct vcpu_svm *svm)
 {
 	++svm->vcpu.stat.nmi_window_exits;
@@ -2418,7 +2428,7 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm) = {
 	/* [SVM_EXIT_CR0_SEL_WRITE]		= emulate_on_interception, */
 	[SVM_EXIT_CPUID]			= cpuid_interception,
 	[SVM_EXIT_IRET]                         = iret_interception,
-	[SVM_EXIT_INVD]                         = emulate_on_interception,
+	[SVM_EXIT_INVD]                         = invd_interception,
 	[SVM_EXIT_PAUSE]			= pause_interception,
 	[SVM_EXIT_HLT]				= halt_interception,
 	[SVM_EXIT_INVLPG]			= invlpg_interception,
@@ -2434,7 +2444,7 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm) = {
 	[SVM_EXIT_STGI]				= stgi_interception,
 	[SVM_EXIT_CLGI]				= clgi_interception,
 	[SVM_EXIT_SKINIT]			= skinit_interception,
-	[SVM_EXIT_WBINVD]                       = emulate_on_interception,
+	[SVM_EXIT_WBINVD]                       = invd_interception,
 	[SVM_EXIT_MONITOR]			= invalid_op_interception,
 	[SVM_EXIT_MWAIT]			= invalid_op_interception,
 	[SVM_EXIT_NPF]				= pf_interception,
-- 
1.6.6


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