linux-kernel - [PATCH v2 1/2] KVM: SVM: Add a dedicated INVD intercept routine

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Date:   Thu, 24 Sep 2020 13:41:57 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     kvm@...r.kernel.org, x86@...nel.org, linux-kernel@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Brijesh Singh <brijesh.singh@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v2 1/2] KVM: SVM: Add a dedicated INVD intercept routine

From: Tom Lendacky <thomas.lendacky@....com>

The INVD instruction intercept performs emulation. Emulation can't be done
on an SEV guest because the guest memory is encrypted.

Provide a dedicated intercept routine for the INVD intercept. And since
the instruction is emulated as a NOP, just skip it instead.

Fixes: 1654efcbc431 ("KVM: SVM: Add KVM_SEV_INIT command")
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kvm/svm/svm.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index c91acabf18d0..66d225899781 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2183,6 +2183,12 @@ static int iret_interception(struct vcpu_svm *svm)
 	return 1;
 }
 
+static int invd_interception(struct vcpu_svm *svm)
+{
+	/* Treat an INVD instruction as a NOP and just skip it. */
+	return kvm_skip_emulated_instruction(&svm->vcpu);
+}
+
 static int invlpg_interception(struct vcpu_svm *svm)
 {
 	if (!static_cpu_has(X86_FEATURE_DECODEASSISTS))
@@ -2774,7 +2780,7 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
 	[SVM_EXIT_RDPMC]			= rdpmc_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,
-- 
2.28.0