KVM: VMX: Frame in ENCLS handler for SGX virtualization

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>
Message-Id: <1c782269608b2f5e1034be450f375a8432fb705d.1618196135.git.kai.huang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 1b4766f..87f514c 100644 (file)
--- 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 (file)
index 0000000..d874eb1
--- /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)kvm_rax_read(vcpu);
+
+       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 (file)
index 0000000..6e17ecd
--- /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 09f2c9e..d210364 100644 (file)
--- 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"
@@ -5607,16 +5608,18 @@ 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)
 {