[PATCH v3 20/25] KVM: VMX: Frame in ENCLS handler for SGX virtualization

Kai Huang
2021-03-19T07:25:06Z

From: Sean Christopherson <sean.j.christopherson@intel.com>

Introduce sgx.c and sgx.h, along with the framework for handling ENCLS
VM-Exits. Add a bool, enable_sgx, that will eventually be wired up to a
module param to control whether or not SGX virtualization is enabled at
runtime.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
---
arch/x86/kvm/Makefile | 2 ++
arch/x86/kvm/vmx/sgx.c | 50 ++++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/vmx/sgx.h | 15 +++++++++++++
arch/x86/kvm/vmx/vmx.c | 9 +++++---
4 files changed, 73 insertions(+), 3 deletions(-)
create mode 100644 arch/x86/kvm/vmx/sgx.c
create mode 100644 arch/x86/kvm/vmx/sgx.h

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 1b4766fe1de2..87f514c36eae 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -23,6 +23,8 @@ kvm-$(CONFIG_KVM_XEN) += xen.o

kvm-intel-y += vmx/vmx.o vmx/vmenter.o vmx/pmu_intel.o vmx/vmcs12.o \
vmx/evmcs.o vmx/nested.o vmx/posted_intr.o
+kvm-intel-$(CONFIG_X86_SGX_KVM) += vmx/sgx.o
+
kvm-amd-y += svm/svm.o svm/vmenter.o svm/pmu.o svm/nested.o svm/avic.o svm/sev.o

obj-$(CONFIG_KVM) += kvm.o
diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
new file mode 100644
index 000000000000..f68adbe38750
--- /dev/null
+++ b/arch/x86/kvm/vmx/sgx.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2021 Intel Corporation. */
+
+#include <asm/sgx.h>
+
+#include "cpuid.h"
+#include "kvm_cache_regs.h"
+#include "sgx.h"
+#include "vmx.h"
+#include "x86.h"
+
+bool __read_mostly enable_sgx;
+
+static inline bool encls_leaf_enabled_in_guest(struct kvm_vcpu *vcpu, u32 leaf)
+{
+ if (!enable_sgx || !guest_cpuid_has(vcpu, X86_FEATURE_SGX))
+ return false;
+
+ if (leaf >= ECREATE && leaf <= ETRACK)
+ return guest_cpuid_has(vcpu, X86_FEATURE_SGX1);
+
+ if (leaf >= EAUG && leaf <= EMODT)
+ return guest_cpuid_has(vcpu, X86_FEATURE_SGX2);
+
+ return false;
+}
+
+static inline bool sgx_enabled_in_guest_bios(struct kvm_vcpu *vcpu)
+{
+ const u64 bits = FEAT_CTL_SGX_ENABLED | FEAT_CTL_LOCKED;
+
+ return (to_vmx(vcpu)->msr_ia32_feature_control & bits) == bits;
+}
+
+int handle_encls(struct kvm_vcpu *vcpu)
+{
+ u32 leaf = (u32)vcpu->arch.regs[VCPU_REGS_RAX];
+
+ if (!encls_leaf_enabled_in_guest(vcpu, leaf)) {
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ } else if (!sgx_enabled_in_guest_bios(vcpu)) {
+ kvm_inject_gp(vcpu, 0);
+ } else {
+ WARN(1, "KVM: unexpected exit on ENCLS[%u]", leaf);
+ vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
+ vcpu->run->hw.hardware_exit_reason = EXIT_REASON_ENCLS;
+ return 0;
+ }
+ return 1;
+}
diff --git a/arch/x86/kvm/vmx/sgx.h b/arch/x86/kvm/vmx/sgx.h
new file mode 100644
index 000000000000..6e17ecd4aca3
--- /dev/null
+++ b/arch/x86/kvm/vmx/sgx.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __KVM_X86_SGX_H
+#define __KVM_X86_SGX_H
+
+#include <linux/kvm_host.h>
+
+#ifdef CONFIG_X86_SGX_KVM
+extern bool __read_mostly enable_sgx;
+
+int handle_encls(struct kvm_vcpu *vcpu);
+#else
+#define enable_sgx 0
+#endif
+
+#endif /* __KVM_X86_SGX_H */
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 9dd185a53a3e..ef668047a8f9 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -57,6 +57,7 @@
#include "mmu.h"
#include "nested.h"
#include "pmu.h"
+#include "sgx.h"
#include "trace.h"
#include "vmcs.h"
#include "vmcs12.h"
@@ -5673,16 +5674,18 @@ static int handle_vmx_instruction(struct kvm_vcpu *vcpu)
return 1;
}

+#ifndef CONFIG_X86_SGX_KVM
static int handle_encls(struct kvm_vcpu *vcpu)
{
/*
- * SGX virtualization is not yet supported. There is no software
- * enable bit for SGX, so we have to trap ENCLS and inject a #UD
- * to prevent the guest from executing ENCLS.
+ * SGX virtualization is disabled. There is no software enable bit for
+ * SGX, so KVM intercepts all ENCLS leafs and injects a #UD to prevent
+ * the guest from executing ENCLS (when SGX is supported by hardware).
*/
kvm_queue_exception(vcpu, UD_VECTOR);
return 1;
}
+#endif /* CONFIG_X86_SGX_KVM */

static int handle_bus_lock_vmexit(struct kvm_vcpu *vcpu)
{
--
2.30.2