From b33bb78a1fada6445c265c585ee0dd0fc6279102 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Tue, 22 Jun 2021 10:22:44 -0700
Subject: [PATCH] KVM: nVMX: Handle split-lock #AC exceptions that happen in L2
Git-commit: b33bb78a1fada6445c265c585ee0dd0fc6279102
Patch-mainline: v5.14-rc1
References: bsc#1187959

Mark #ACs that won't be reinjected to the guest as wanted by L0 so that
KVM handles split-lock #AC from L2 instead of forwarding the exception to
L1.  Split-lock #AC isn't yet virtualized, i.e. L1 will treat it like a
regular #AC and do the wrong thing, e.g. reinject it into L2.

Fixes: e6f8b6c12f03 ("KVM: VMX: Extend VMXs #AC interceptor to handle split lock #AC in guest")
Cc: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210622172244.3561540-1-seanjc@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Acked-by: Dario Faggioli <dfaggioli@suse.com>
---
 arch/x86/kvm/vmx/nested.c | 3 +++
 arch/x86/kvm/vmx/vmcs.h   | 5 +++++
 arch/x86/kvm/vmx/vmx.c    | 4 ++--
 arch/x86/kvm/vmx/vmx.h    | 1 +
 4 files changed, 11 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/vmx/vmcs.h
+++ b/arch/x86/kvm/vmx/vmcs.h
@@ -104,6 +104,11 @@ static inline bool is_gp_fault(u32 intr_
 	return is_exception_n(intr_info, GP_VECTOR);
 }
 
+static inline bool is_alignment_check(u32 intr_info)
+{
+	return is_exception_n(intr_info, AC_VECTOR);
+}
+
 static inline bool is_machine_check(u32 intr_info)
 {
 	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK |
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4656,7 +4656,7 @@ static int handle_machine_check(struct k
  *  - Guest has #AC detection enabled in CR0
  *  - Guest EFLAGS has AC bit set
  */
-static inline bool guest_inject_ac(struct kvm_vcpu *vcpu)
+bool vmx_guest_inject_ac(struct kvm_vcpu *vcpu)
 {
 	if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT))
 		return true;
@@ -4756,7 +4756,7 @@ static int handle_exception_nmi(struct k
 		kvm_run->debug.arch.exception = ex_no;
 		break;
 	case AC_VECTOR:
-		if (guest_inject_ac(vcpu)) {
+		if (vmx_guest_inject_ac(vcpu)) {
 			kvm_queue_exception_e(vcpu, AC_VECTOR, error_code);
 			return 1;
 		}