KVM: x86: smm: use smram structs in the common code

Use kvm_smram union instad of raw arrays in the common smm code.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20221025124741.228045-18-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -206,6 +206,7 @@ typedef enum exit_fastpath_completion fastpath_t;
 
 struct x86_emulate_ctxt;
 struct x86_exception;
+union kvm_smram;
 enum x86_intercept;
 enum x86_intercept_stage;
 
@@ -1616,8 +1617,8 @@ struct kvm_x86_ops {
 
 #ifdef CONFIG_KVM_SMM
 	int (*smi_allowed)(struct kvm_vcpu *vcpu, bool for_injection);
-	int (*enter_smm)(struct kvm_vcpu *vcpu, char *smstate);
-	int (*leave_smm)(struct kvm_vcpu *vcpu, const char *smstate);
+	int (*enter_smm)(struct kvm_vcpu *vcpu, union kvm_smram *smram);
+	int (*leave_smm)(struct kvm_vcpu *vcpu, const union kvm_smram *smram);
 	void (*enable_smi_window)(struct kvm_vcpu *vcpu);
 #endif
 

arch/x86/kvm/smm.c

@@ -295,17 +295,18 @@ void enter_smm(struct kvm_vcpu *vcpu)
 	struct kvm_segment cs, ds;
 	struct desc_ptr dt;
 	unsigned long cr0;
-	char buf[512];
+	union kvm_smram smram;
 
 	check_smram_offsets();
 
-	memset(buf, 0, 512);
+	memset(smram.bytes, 0, sizeof(smram.bytes));
+
 #ifdef CONFIG_X86_64
 	if (guest_cpuid_has(vcpu, X86_FEATURE_LM))
-		enter_smm_save_state_64(vcpu, buf);
+		enter_smm_save_state_64(vcpu, smram.bytes);
 	else
 #endif
-		enter_smm_save_state_32(vcpu, buf);
+		enter_smm_save_state_32(vcpu, smram.bytes);
 
 	/*
 	 * Give enter_smm() a chance to make ISA-specific changes to the vCPU
@@ -315,12 +316,12 @@ void enter_smm(struct kvm_vcpu *vcpu)
 	 * Kill the VM in the unlikely case of failure, because the VM
 	 * can be in undefined state in this case.
 	 */
-	if (static_call(kvm_x86_enter_smm)(vcpu, buf))
+	if (static_call(kvm_x86_enter_smm)(vcpu, &smram))
 		goto error;
 
 	kvm_smm_changed(vcpu, true);
 
-	if (kvm_vcpu_write_guest(vcpu, vcpu->arch.smbase + 0xfe00, buf, sizeof(buf)))
+	if (kvm_vcpu_write_guest(vcpu, vcpu->arch.smbase + 0xfe00, &smram, sizeof(smram)))
 		goto error;
 
 	if (static_call(kvm_x86_get_nmi_mask)(vcpu))
@@ -480,7 +481,7 @@ static int rsm_enter_protected_mode(struct kvm_vcpu *vcpu,
 }
 
 static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,
-			     const char *smstate)
+			     u8 *smstate)
 {
 	struct kvm_vcpu *vcpu = ctxt->vcpu;
 	struct kvm_segment desc;
@@ -541,7 +542,7 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,
 
 #ifdef CONFIG_X86_64
 static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,
-			     const char *smstate)
+			     u8 *smstate)
 {
 	struct kvm_vcpu *vcpu = ctxt->vcpu;
 	struct kvm_segment desc;
@@ -612,13 +613,13 @@ int emulator_leave_smm(struct x86_emulate_ctxt *ctxt)
 {
 	struct kvm_vcpu *vcpu = ctxt->vcpu;
 	unsigned long cr0;
-	char buf[512];
+	union kvm_smram smram;
 	u64 smbase;
 	int ret;
 
 	smbase = vcpu->arch.smbase;
 
-	ret = kvm_vcpu_read_guest(vcpu, smbase + 0xfe00, buf, sizeof(buf));
+	ret = kvm_vcpu_read_guest(vcpu, smbase + 0xfe00, smram.bytes, sizeof(smram));
 	if (ret < 0)
 		return X86EMUL_UNHANDLEABLE;
 
@@ -675,13 +676,13 @@ int emulator_leave_smm(struct x86_emulate_ctxt *ctxt)
 	 * state (e.g. enter guest mode) before loading state from the SMM
 	 * state-save area.
 	 */
-	if (static_call(kvm_x86_leave_smm)(vcpu, buf))
+	if (static_call(kvm_x86_leave_smm)(vcpu, &smram))
 		return X86EMUL_UNHANDLEABLE;
 
 #ifdef CONFIG_X86_64
 	if (guest_cpuid_has(vcpu, X86_FEATURE_LM))
-		return rsm_load_state_64(ctxt, buf);
+		return rsm_load_state_64(ctxt, smram.bytes);
 	else
 #endif
-		return rsm_load_state_32(ctxt, buf);
+		return rsm_load_state_32(ctxt, smram.bytes);
 }

arch/x86/kvm/svm/svm.c

@@ -4401,12 +4401,14 @@ static int svm_smi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
 	return 1;
 }
 
-static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
+static int svm_enter_smm(struct kvm_vcpu *vcpu, union kvm_smram *smram)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct kvm_host_map map_save;
 	int ret;
 
+	char *smstate = (char *)smram;
+
 	if (!is_guest_mode(vcpu))
 		return 0;
 
@@ -4448,7 +4450,7 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
 	return 0;
 }
 
-static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
+static int svm_leave_smm(struct kvm_vcpu *vcpu, const union kvm_smram *smram)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct kvm_host_map map, map_save;
@@ -4456,6 +4458,8 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
 	struct vmcb *vmcb12;
 	int ret;
 
+	const char *smstate = (const char *)smram;
+
 	if (!guest_cpuid_has(vcpu, X86_FEATURE_LM))
 		return 0;
 

arch/x86/kvm/vmx/vmx.c

@@ -7941,7 +7941,7 @@ static int vmx_smi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
 	return !is_smm(vcpu);
 }
 
-static int vmx_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
+static int vmx_enter_smm(struct kvm_vcpu *vcpu, union kvm_smram *smram)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 
@@ -7962,7 +7962,7 @@ static int vmx_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
 	return 0;
 }
 
-static int vmx_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
+static int vmx_leave_smm(struct kvm_vcpu *vcpu, const union kvm_smram *smram)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	int ret;