1 files changed, 32 insertions, 0 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b5b128a0a051..426039285fd1 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -7098,6 +7098,36 @@ static int nested_enable_evmcs(struct kvm_vcpu *vcpu,
         return -ENODEV;
 }
 
+static bool svm_need_emulation_on_page_fault(struct kvm_vcpu *vcpu)
+{
+        bool is_user, smap;
+
+        is_user = svm_get_cpl(vcpu) == 3;
+        smap = !kvm_read_cr4_bits(vcpu, X86_CR4_SMAP);
+
+        /*
+         * Detect and workaround Errata 1096 Fam_17h_00_0Fh
+         *
+         * In non SEV guest, hypervisor will be able to read the guest
+         * memory to decode the instruction pointer when insn_len is zero
+         * so we return true to indicate that decoding is possible.
+         *
+         * But in the SEV guest, the guest memory is encrypted with the
+         * guest specific key and hypervisor will not be able to decode the
+         * instruction pointer so we will not able to workaround it. Lets
+         * print the error and request to kill the guest.
+         */
+        if (is_user && smap) {
+                if (!sev_guest(vcpu->kvm))
+                        return true;
+
+                pr_err_ratelimited("KVM: Guest triggered AMD Erratum 1096\n");
+                kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
+        }
+
+        return false;
+}
+
 static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
         .cpu_has_kvm_support = has_svm,
         .disabled_by_bios = is_disabled,
@@ -7231,6 +7261,8 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 
         .nested_enable_evmcs = nested_enable_evmcs,
         .nested_get_evmcs_version = nested_get_evmcs_version,
+
+        .need_emulation_on_page_fault = svm_need_emulation_on_page_fault,
 };
 
 static int __init svm_init(void)