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From: Tom Lendacky <thomas.lendacky@amd.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Brijesh Singh <brijesh.singh@amd.com>
Subject: [PATCH v3 07/34] KVM: SVM: Add required changes to support intercepts under SEV-ES
Date: Mon,  9 Nov 2020 16:25:33 -0600	[thread overview]
Message-ID: <6d21d1d7d0e650217d948b4602a8be8ebc1aa57b.1604960760.git.thomas.lendacky@amd.com> (raw)
In-Reply-To: <cover.1604960760.git.thomas.lendacky@amd.com>

From: Tom Lendacky <thomas.lendacky@amd.com>

When a guest is running under SEV-ES, the hypervisor cannot access the
guest register state. There are numerous places in the KVM code where
certain registers are accessed that are not allowed to be accessed (e.g.
RIP, CR0, etc). Add checks to prevent register accesses and add intercept
update support at various points within the KVM code.

Also, when handling a VMGEXIT, exceptions are passed back through the
GHCB. Since the RDMSR/WRMSR intercepts (may) inject a #GP on error,
update the SVM intercepts to handle this for SEV-ES guests.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/include/asm/svm.h |   3 +-
 arch/x86/kvm/svm/svm.c     | 111 +++++++++++++++++++++++++++++++++----
 arch/x86/kvm/x86.c         |   6 +-
 3 files changed, 107 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 1edf24f51b53..bce28482d63d 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -178,7 +178,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #define LBR_CTL_ENABLE_MASK BIT_ULL(0)
 #define VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK BIT_ULL(1)
 
-#define SVM_INTERRUPT_SHADOW_MASK 1
+#define SVM_INTERRUPT_SHADOW_MASK	BIT_ULL(0)
+#define SVM_GUEST_INTERRUPT_MASK	BIT_ULL(1)
 
 #define SVM_IOIO_STR_SHIFT 2
 #define SVM_IOIO_REP_SHIFT 3
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index d45b2dc5cabe..9a3d57ed997f 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -36,6 +36,7 @@
 #include <asm/mce.h>
 #include <asm/spec-ctrl.h>
 #include <asm/cpu_device_id.h>
+#include <asm/traps.h>
 
 #include <asm/virtext.h>
 #include "trace.h"
@@ -340,6 +341,13 @@ static int skip_emulated_instruction(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
+	/*
+	 * SEV-ES does not expose the next RIP. The RIP update is controlled by
+	 * the type of exit and the #VC handler in the guest.
+	 */
+	if (sev_es_guest(vcpu->kvm))
+		goto done;
+
 	if (nrips && svm->vmcb->control.next_rip != 0) {
 		WARN_ON_ONCE(!static_cpu_has(X86_FEATURE_NRIPS));
 		svm->next_rip = svm->vmcb->control.next_rip;
@@ -351,6 +359,8 @@ static int skip_emulated_instruction(struct kvm_vcpu *vcpu)
 	} else {
 		kvm_rip_write(vcpu, svm->next_rip);
 	}
+
+done:
 	svm_set_interrupt_shadow(vcpu, 0);
 
 	return 1;
@@ -1651,9 +1661,18 @@ static void svm_set_gdt(struct kvm_vcpu *vcpu, struct desc_ptr *dt)
 
 static void update_cr0_intercept(struct vcpu_svm *svm)
 {
-	ulong gcr0 = svm->vcpu.arch.cr0;
-	u64 *hcr0 = &svm->vmcb->save.cr0;
+	ulong gcr0;
+	u64 *hcr0;
+
+	/*
+	 * SEV-ES guests must always keep the CR intercepts cleared. CR
+	 * tracking is done using the CR write traps.
+	 */
+	if (sev_es_guest(svm->vcpu.kvm))
+		return;
 
+	gcr0 = svm->vcpu.arch.cr0;
+	hcr0 = &svm->vmcb->save.cr0;
 	*hcr0 = (*hcr0 & ~SVM_CR0_SELECTIVE_MASK)
 		| (gcr0 & SVM_CR0_SELECTIVE_MASK);
 
@@ -1673,7 +1692,7 @@ void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 	struct vcpu_svm *svm = to_svm(vcpu);
 
 #ifdef CONFIG_X86_64
-	if (vcpu->arch.efer & EFER_LME) {
+	if (vcpu->arch.efer & EFER_LME && !vcpu->arch.guest_state_protected) {
 		if (!is_paging(vcpu) && (cr0 & X86_CR0_PG)) {
 			vcpu->arch.efer |= EFER_LMA;
 			svm->vmcb->save.efer |= EFER_LMA | EFER_LME;
@@ -2604,7 +2623,29 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 
 static int rdmsr_interception(struct vcpu_svm *svm)
 {
-	return kvm_emulate_rdmsr(&svm->vcpu);
+	u32 ecx;
+	u64 data;
+
+	if (!sev_es_guest(svm->vcpu.kvm))
+		return kvm_emulate_rdmsr(&svm->vcpu);
+
+	ecx = kvm_rcx_read(&svm->vcpu);
+	if (kvm_get_msr(&svm->vcpu, ecx, &data)) {
+		trace_kvm_msr_read_ex(ecx);
+		ghcb_set_sw_exit_info_1(svm->ghcb, 1);
+		ghcb_set_sw_exit_info_2(svm->ghcb,
+					X86_TRAP_GP |
+					SVM_EVTINJ_TYPE_EXEPT |
+					SVM_EVTINJ_VALID);
+		return 1;
+	}
+
+	trace_kvm_msr_read(ecx, data);
+
+	kvm_rax_write(&svm->vcpu, data & -1u);
+	kvm_rdx_write(&svm->vcpu, (data >> 32) & -1u);
+
+	return kvm_skip_emulated_instruction(&svm->vcpu);
 }
 
 static int svm_set_vm_cr(struct kvm_vcpu *vcpu, u64 data)
@@ -2793,7 +2834,27 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 
 static int wrmsr_interception(struct vcpu_svm *svm)
 {
-	return kvm_emulate_wrmsr(&svm->vcpu);
+	u32 ecx;
+	u64 data;
+
+	if (!sev_es_guest(svm->vcpu.kvm))
+		return kvm_emulate_wrmsr(&svm->vcpu);
+
+	ecx = kvm_rcx_read(&svm->vcpu);
+	data = kvm_read_edx_eax(&svm->vcpu);
+	if (kvm_set_msr(&svm->vcpu, ecx, data)) {
+		trace_kvm_msr_write_ex(ecx, data);
+		ghcb_set_sw_exit_info_1(svm->ghcb, 1);
+		ghcb_set_sw_exit_info_2(svm->ghcb,
+					X86_TRAP_GP |
+					SVM_EVTINJ_TYPE_EXEPT |
+					SVM_EVTINJ_VALID);
+		return 1;
+	}
+
+	trace_kvm_msr_write(ecx, data);
+
+	return kvm_skip_emulated_instruction(&svm->vcpu);
 }
 
 static int msr_interception(struct vcpu_svm *svm)
@@ -2823,7 +2884,14 @@ static int interrupt_window_interception(struct vcpu_svm *svm)
 static int pause_interception(struct vcpu_svm *svm)
 {
 	struct kvm_vcpu *vcpu = &svm->vcpu;
-	bool in_kernel = (svm_get_cpl(vcpu) == 0);
+	bool in_kernel;
+
+	/*
+	 * CPL is not made available for an SEV-ES guest, so just set in_kernel
+	 * to true.
+	 */
+	in_kernel = (sev_es_guest(svm->vcpu.kvm)) ? true
+						  : (svm_get_cpl(vcpu) == 0);
 
 	if (!kvm_pause_in_guest(vcpu->kvm))
 		grow_ple_window(vcpu);
@@ -3086,10 +3154,13 @@ static int handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
 
 	trace_kvm_exit(exit_code, vcpu, KVM_ISA_SVM);
 
-	if (!svm_is_intercept(svm, INTERCEPT_CR0_WRITE))
-		vcpu->arch.cr0 = svm->vmcb->save.cr0;
-	if (npt_enabled)
-		vcpu->arch.cr3 = svm->vmcb->save.cr3;
+	/* SEV-ES guests must use the CR write traps to track CR registers. */
+	if (!sev_es_guest(vcpu->kvm)) {
+		if (!svm_is_intercept(svm, INTERCEPT_CR0_WRITE))
+			vcpu->arch.cr0 = svm->vmcb->save.cr0;
+		if (npt_enabled)
+			vcpu->arch.cr3 = svm->vmcb->save.cr3;
+	}
 
 	if (is_guest_mode(vcpu)) {
 		int vmexit;
@@ -3201,6 +3272,13 @@ static void update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
+	/*
+	 * SEV-ES guests must always keep the CR intercepts cleared. CR
+	 * tracking is done using the CR write traps.
+	 */
+	if (sev_es_guest(vcpu->kvm))
+		return;
+
 	if (nested_svm_virtualize_tpr(vcpu))
 		return;
 
@@ -3269,6 +3347,13 @@ bool svm_interrupt_blocked(struct kvm_vcpu *vcpu)
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct vmcb *vmcb = svm->vmcb;
 
+	/*
+	 * SEV-ES guests to not expose RFLAGS. Use the VMCB interrupt mask
+	 * bit to determine the state of the IF flag.
+	 */
+	if (sev_es_guest(svm->vcpu.kvm))
+		return !(vmcb->control.int_state & SVM_GUEST_INTERRUPT_MASK);
+
 	if (!gif_set(svm))
 		return true;
 
@@ -3454,6 +3539,12 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)
 		svm->vcpu.arch.nmi_injected = true;
 		break;
 	case SVM_EXITINTINFO_TYPE_EXEPT:
+		/*
+		 * Never re-inject a #VC exception.
+		 */
+		if (vector == X86_TRAP_VC)
+			break;
+
 		/*
 		 * In case of software exceptions, do not reinject the vector,
 		 * but re-execute the instruction instead. Rewind RIP first
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 447edc0d1d5a..3aafbd2540be 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3997,7 +3997,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
 	int idx;
 
-	if (vcpu->preempted)
+	if (vcpu->preempted && !vcpu->arch.guest_state_protected)
 		vcpu->arch.preempted_in_kernel = !kvm_x86_ops.get_cpl(vcpu);
 
 	/*
@@ -8156,7 +8156,9 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu)
 {
 	struct kvm_run *kvm_run = vcpu->run;
 
-	kvm_run->if_flag = (kvm_get_rflags(vcpu) & X86_EFLAGS_IF) != 0;
+	kvm_run->if_flag = (vcpu->arch.guest_state_protected)
+		? kvm_arch_interrupt_allowed(vcpu)
+		: (kvm_get_rflags(vcpu) & X86_EFLAGS_IF) != 0;
 	kvm_run->flags = is_smm(vcpu) ? KVM_RUN_X86_SMM : 0;
 	kvm_run->cr8 = kvm_get_cr8(vcpu);
 	kvm_run->apic_base = kvm_get_apic_base(vcpu);
-- 
2.28.0


  parent reply	other threads:[~2020-11-09 22:27 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-09 22:25 [PATCH v3 00/34] SEV-ES hypervisor support Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 01/34] x86/cpu: Add VM page flush MSR availablility as a CPUID feature Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 02/34] KVM: SVM: Remove the call to sev_platform_status() during setup Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 03/34] KVM: SVM: Add support for SEV-ES capability in KVM Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 04/34] KVM: SVM: Add GHCB accessor functions for retrieving fields Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 05/34] KVM: SVM: Add support for the SEV-ES VMSA Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 06/34] KVM: x86: Mark GPRs dirty when written Tom Lendacky
2020-11-09 22:25 ` Tom Lendacky [this message]
2020-11-09 22:25 ` [PATCH v3 08/34] KVM: SVM: Prevent debugging under SEV-ES Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 09/34] KVM: SVM: Do not allow instruction emulation " Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 10/34] KVM: SVM: Cannot re-initialize the VMCB after shutdown with SEV-ES Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 11/34] KVM: SVM: Prepare for SEV-ES exit handling in the sev.c file Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 12/34] KVM: SVM: Add initial support for a VMGEXIT VMEXIT Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 13/34] KVM: SVM: Create trace events for VMGEXIT processing Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 14/34] KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x002 Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 15/34] KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x004 Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 16/34] KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x100 Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 17/34] KVM: SVM: Create trace events for VMGEXIT MSR protocol processing Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 18/34] KVM: SVM: Support MMIO for an SEV-ES guest Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 19/34] KVM: SVM: Support string IO operations " Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 20/34] KVM: SVM: Add support for EFER write traps " Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 21/34] KVM: SVM: Add support for CR0 " Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 22/34] KVM: SVM: Add support for CR4 " Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 23/34] KVM: SVM: Add support for CR8 " Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 24/34] KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 25/34] KVM: SVM: Do not report support for SMM for an SEV-ES guest Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 26/34] KVM: SVM: Guest FPU state save/restore not needed for " Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 27/34] KVM: SVM: Add support for booting APs for an " Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 28/34] KVM: SVM: Add NMI support " Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 29/34] KVM: SVM: Set the encryption mask for the SVM host save area Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 30/34] KVM: SVM: Update ASID allocation to support SEV-ES guests Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 31/34] KVM: SVM: Provide support for SEV-ES vCPU creation/loading Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 32/34] KVM: SVM: Provide support for SEV-ES vCPU loading Tom Lendacky
2020-11-09 22:25 ` [PATCH v3 33/34] KVM: SVM: Provide an updated VMRUN invocation for SEV-ES guests Tom Lendacky
2020-11-09 22:26 ` [PATCH v3 34/34] KVM: SVM: Provide support to launch and run an SEV-ES guest Tom Lendacky

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