Merge tag 'kvm-x86-svm-6.7' of https://github.com/kvm-x86/linux into HEAD

KVM SVM changes for 6.7:

 - Report KVM_EXIT_SHUTDOWN instead of EINVAL if KVM intercepts SHUTDOWN while
   running an SEV-ES guest.

 - Clean up handling "failures" when KVM detects it can't emulate the "skip"
   action for an instruction that has already been partially emulated.  Drop a
   hack in the SVM code that was fudging around the emulator code not giving
   SVM enough information to do the right thing.

Author: bonzini

arch/x86/include/asm/kvm-x86-ops.h

@@ -127,7 +127,7 @@ KVM_X86_OP_OPTIONAL(vm_copy_enc_context_from)
 KVM_X86_OP_OPTIONAL(vm_move_enc_context_from)
 KVM_X86_OP_OPTIONAL(guest_memory_reclaimed)
 KVM_X86_OP(get_msr_feature)
-KVM_X86_OP(can_emulate_instruction)
+KVM_X86_OP(check_emulate_instruction)
 KVM_X86_OP(apic_init_signal_blocked)
 KVM_X86_OP_OPTIONAL(enable_l2_tlb_flush)
 KVM_X86_OP_OPTIONAL(migrate_timers)

arch/x86/include/asm/kvm_host.h

@@ -1745,8 +1745,8 @@ struct kvm_x86_ops {
 
 	int (*get_msr_feature)(struct kvm_msr_entry *entry);
 
-	bool (*can_emulate_instruction)(struct kvm_vcpu *vcpu, int emul_type,
-					void *insn, int insn_len);
+	int (*check_emulate_instruction)(struct kvm_vcpu *vcpu, int emul_type,
+					 void *insn, int insn_len);
 
 	bool (*apic_init_signal_blocked)(struct kvm_vcpu *vcpu);
 	int (*enable_l2_tlb_flush)(struct kvm_vcpu *vcpu);

arch/x86/kvm/svm/svm.c

@@ -364,8 +364,6 @@ static void svm_set_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)
 		svm->vmcb->control.int_state |= SVM_INTERRUPT_SHADOW_MASK;
 
 }
-static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
-					void *insn, int insn_len);
 
 static int __svm_skip_emulated_instruction(struct kvm_vcpu *vcpu,
 					   bool commit_side_effects)
@@ -386,14 +384,6 @@ static int __svm_skip_emulated_instruction(struct kvm_vcpu *vcpu,
 	}
 
 	if (!svm->next_rip) {
-		/*
-		 * FIXME: Drop this when kvm_emulate_instruction() does the
-		 * right thing and treats "can't emulate" as outright failure
-		 * for EMULTYPE_SKIP.
-		 */
-		if (!svm_can_emulate_instruction(vcpu, EMULTYPE_SKIP, NULL, 0))
-			return 0;
-
 		if (unlikely(!commit_side_effects))
 			old_rflags = svm->vmcb->save.rflags;
 
@@ -2202,12 +2192,6 @@ static int shutdown_interception(struct kvm_vcpu *vcpu)
 	struct kvm_run *kvm_run = vcpu->run;
 	struct vcpu_svm *svm = to_svm(vcpu);
 
-	/*
-	 * The VM save area has already been encrypted so it
-	 * cannot be reinitialized - just terminate.
-	 */
-	if (sev_es_guest(vcpu->kvm))
-		return -EINVAL;
 
 	/*
 	 * VMCB is undefined after a SHUTDOWN intercept.  INIT the vCPU to put
@@ -2216,9 +2200,14 @@ static int shutdown_interception(struct kvm_vcpu *vcpu)
 	 * userspace.  At a platform view, INIT is acceptable behavior as
 	 * there exist bare metal platforms that automatically INIT the CPU
 	 * in response to shutdown.
+	 *
+	 * The VM save area for SEV-ES guests has already been encrypted so it
+	 * cannot be reinitialized, i.e. synthesizing INIT is futile.
 	 */
-	clear_page(svm->vmcb);
-	kvm_vcpu_reset(vcpu, true);
+	if (!sev_es_guest(vcpu->kvm)) {
+		clear_page(svm->vmcb);
+		kvm_vcpu_reset(vcpu, true);
+	}
 
 	kvm_run->exit_reason = KVM_EXIT_SHUTDOWN;
 	return 0;
@@ -4727,15 +4716,15 @@ static void svm_enable_smi_window(struct kvm_vcpu *vcpu)
 }
 #endif
 
-static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
-					void *insn, int insn_len)
+static int svm_check_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
+					 void *insn, int insn_len)
 {
 	bool smep, smap, is_user;
 	u64 error_code;
 
 	/* Emulation is always possible when KVM has access to all guest state. */
 	if (!sev_guest(vcpu->kvm))
-		return true;
+		return X86EMUL_CONTINUE;
 
 	/* #UD and #GP should never be intercepted for SEV guests. */
 	WARN_ON_ONCE(emul_type & (EMULTYPE_TRAP_UD |
@@ -4747,14 +4736,14 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
 	 * to guest register state.
 	 */
 	if (sev_es_guest(vcpu->kvm))
-		return false;
+		return X86EMUL_RETRY_INSTR;
 
 	/*
 	 * Emulation is possible if the instruction is already decoded, e.g.
 	 * when completing I/O after returning from userspace.
 	 */
 	if (emul_type & EMULTYPE_NO_DECODE)
-		return true;
+		return X86EMUL_CONTINUE;
 
 	/*
 	 * Emulation is possible for SEV guests if and only if a prefilled
@@ -4780,9 +4769,11 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
 	 * success (and in practice it will work the vast majority of the time).
 	 */
 	if (unlikely(!insn)) {
-		if (!(emul_type & EMULTYPE_SKIP))
-			kvm_queue_exception(vcpu, UD_VECTOR);
-		return false;
+		if (emul_type & EMULTYPE_SKIP)
+			return X86EMUL_UNHANDLEABLE;
+
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		return X86EMUL_PROPAGATE_FAULT;
 	}
 
 	/*
@@ -4793,7 +4784,7 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
 	 * table used to translate CS:RIP resides in emulated MMIO.
 	 */
 	if (likely(insn_len))
-		return true;
+		return X86EMUL_CONTINUE;
 
 	/*
 	 * Detect and workaround Errata 1096 Fam_17h_00_0Fh.
@@ -4851,6 +4842,7 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
 			kvm_inject_gp(vcpu, 0);
 		else
 			kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
+		return X86EMUL_PROPAGATE_FAULT;
 	}
 
 resume_guest:
@@ -4868,7 +4860,7 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
 	 * doesn't explicitly define "ignored", i.e. doing nothing and letting
 	 * the guest spin is technically "ignoring" the access.
 	 */
-	return false;
+	return X86EMUL_RETRY_INSTR;
 }
 
 static bool svm_apic_init_signal_blocked(struct kvm_vcpu *vcpu)
@@ -5028,7 +5020,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.vm_copy_enc_context_from = sev_vm_copy_enc_context_from,
 	.vm_move_enc_context_from = sev_vm_move_enc_context_from,
 
-	.can_emulate_instruction = svm_can_emulate_instruction,
+	.check_emulate_instruction = svm_check_emulate_instruction,
 
 	.apic_init_signal_blocked = svm_apic_init_signal_blocked,
 

arch/x86/kvm/vmx/vmx.c

@@ -1657,8 +1657,8 @@ static int vmx_rtit_ctl_check(struct kvm_vcpu *vcpu, u64 data)
 	return 0;
 }
 
-static bool vmx_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
-					void *insn, int insn_len)
+static int vmx_check_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
+					 void *insn, int insn_len)
 {
 	/*
 	 * Emulation of instructions in SGX enclaves is impossible as RIP does
@@ -1669,9 +1669,9 @@ static bool vmx_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
 	 */
 	if (to_vmx(vcpu)->exit_reason.enclave_mode) {
 		kvm_queue_exception(vcpu, UD_VECTOR);
-		return false;
+		return X86EMUL_PROPAGATE_FAULT;
 	}
-	return true;
+	return X86EMUL_CONTINUE;
 }
 
 static int skip_emulated_instruction(struct kvm_vcpu *vcpu)
@@ -5792,7 +5792,7 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
 {
 	gpa_t gpa;
 
-	if (!vmx_can_emulate_instruction(vcpu, EMULTYPE_PF, NULL, 0))
+	if (vmx_check_emulate_instruction(vcpu, EMULTYPE_PF, NULL, 0))
 		return 1;
 
 	/*
@@ -8338,7 +8338,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
 	.enable_smi_window = vmx_enable_smi_window,
 #endif
 
-	.can_emulate_instruction = vmx_can_emulate_instruction,
+	.check_emulate_instruction = vmx_check_emulate_instruction,
 	.apic_init_signal_blocked = vmx_apic_init_signal_blocked,
 	.migrate_timers = vmx_migrate_timers,
 

arch/x86/kvm/x86.c

@@ -7596,11 +7596,11 @@ int kvm_write_guest_virt_system(struct kvm_vcpu *vcpu, gva_t addr, void *val,
 }
 EXPORT_SYMBOL_GPL(kvm_write_guest_virt_system);
 
-static int kvm_can_emulate_insn(struct kvm_vcpu *vcpu, int emul_type,
-				void *insn, int insn_len)
+static int kvm_check_emulate_insn(struct kvm_vcpu *vcpu, int emul_type,
+				  void *insn, int insn_len)
 {
-	return static_call(kvm_x86_can_emulate_instruction)(vcpu, emul_type,
-							    insn, insn_len);
+	return static_call(kvm_x86_check_emulate_instruction)(vcpu, emul_type,
+							      insn, insn_len);
 }
 
 int handle_ud(struct kvm_vcpu *vcpu)
@@ -7610,8 +7610,10 @@ int handle_ud(struct kvm_vcpu *vcpu)
 	int emul_type = EMULTYPE_TRAP_UD;
 	char sig[5]; /* ud2; .ascii "kvm" */
 	struct x86_exception e;
+	int r;
 
-	if (unlikely(!kvm_can_emulate_insn(vcpu, emul_type, NULL, 0)))
+	r = kvm_check_emulate_insn(vcpu, emul_type, NULL, 0);
+	if (r != X86EMUL_CONTINUE)
 		return 1;
 
 	if (fep_flags &&
@@ -8993,8 +8995,14 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;
 	bool writeback = true;
 
-	if (unlikely(!kvm_can_emulate_insn(vcpu, emulation_type, insn, insn_len)))
-		return 1;
+	r = kvm_check_emulate_insn(vcpu, emulation_type, insn, insn_len);
+	if (r != X86EMUL_CONTINUE) {
+		if (r == X86EMUL_RETRY_INSTR || r == X86EMUL_PROPAGATE_FAULT)
+			return 1;
+
+		WARN_ON_ONCE(r != X86EMUL_UNHANDLEABLE);
+		return handle_emulation_failure(vcpu, emulation_type);
+	}
 
 	vcpu->arch.l1tf_flush_l1d = true;