Merge tag 'v5.1-rc3' into devel

Linux 5.1-rc3

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)