[RFC PATCH 20/35] KVM: SVM: Add SEV/SEV-ES support for intercepting INVD

[Tom Lendacky]

From: Tom Lendacky <thomas.lendacky@xxxxxxx>

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

Provide a specific intercept routine for the INVD intercept. Within this
intercept routine, skip the instruction for an SEV or SEV-ES guest since
it is emulated as a NOP anyway.

Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
 arch/x86/kvm/svm/svm.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 37c98e85aa62..ac64a5b128b2 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2275,6 +2275,17 @@ static int iret_interception(struct vcpu_svm *svm)
 	return 1;
 }
 
+static int invd_interception(struct vcpu_svm *svm)
+{
+	/*
+	 * Can't do emulation on any type of SEV guest and INVD is emulated
+	 * as a NOP, so just skip it.
+	 */
+	return (sev_guest(svm->vcpu.kvm))
+		? kvm_skip_emulated_instruction(&svm->vcpu)
+		: kvm_emulate_instruction(&svm->vcpu, 0);
+}
+
 static int invlpg_interception(struct vcpu_svm *svm)
 {
 	if (!static_cpu_has(X86_FEATURE_DECODEASSISTS))
@@ -2912,7 +2923,7 @@ 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