KVM: x86: pass host_initiated to functions that read MSRs

SMBASE is only readable from SMM for the VCPU, but it must be always
accessible if userspace is accessing it.  Thus, all functions that
read MSRs are changed to accept a struct msr_data; the host_initiated
and index fields are pre-initialized, while the data field is filled
on return.

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 29 insertions, 25 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b9f9e10..a08df41 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3069,42 +3069,42 @@ static u64 svm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
 		svm_scale_tsc(vcpu, host_tsc);
 }
 
-static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data)
+static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
-	switch (ecx) {
+	switch (msr_info->index) {
 	case MSR_IA32_TSC: {
-		*data = svm->vmcb->control.tsc_offset +
+		msr_info->data = svm->vmcb->control.tsc_offset +
 			svm_scale_tsc(vcpu, native_read_tsc());
 
 		break;
 	}
 	case MSR_STAR:
-		*data = svm->vmcb->save.star;
+		msr_info->data = svm->vmcb->save.star;
 		break;
 #ifdef CONFIG_X86_64
 	case MSR_LSTAR:
-		*data = svm->vmcb->save.lstar;
+		msr_info->data = svm->vmcb->save.lstar;
 		break;
 	case MSR_CSTAR:
-		*data = svm->vmcb->save.cstar;
+		msr_info->data = svm->vmcb->save.cstar;
 		break;
 	case MSR_KERNEL_GS_BASE:
-		*data = svm->vmcb->save.kernel_gs_base;
+		msr_info->data = svm->vmcb->save.kernel_gs_base;
 		break;
 	case MSR_SYSCALL_MASK:
-		*data = svm->vmcb->save.sfmask;
+		msr_info->data = svm->vmcb->save.sfmask;
 		break;
 #endif
 	case MSR_IA32_SYSENTER_CS:
-		*data = svm->vmcb->save.sysenter_cs;
+		msr_info->data = svm->vmcb->save.sysenter_cs;
 		break;
 	case MSR_IA32_SYSENTER_EIP:
-		*data = svm->sysenter_eip;
+		msr_info->data = svm->sysenter_eip;
 		break;
 	case MSR_IA32_SYSENTER_ESP:
-		*data = svm->sysenter_esp;
+		msr_info->data = svm->sysenter_esp;
 		break;
 	/*
 	 * Nobody will change the following 5 values in the VMCB so we can
@@ -3112,31 +3112,31 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data)
 	 * implemented.
 	 */
 	case MSR_IA32_DEBUGCTLMSR:
-		*data = svm->vmcb->save.dbgctl;
+		msr_info->data = svm->vmcb->save.dbgctl;
 		break;
 	case MSR_IA32_LASTBRANCHFROMIP:
-		*data = svm->vmcb->save.br_from;
+		msr_info->data = svm->vmcb->save.br_from;
 		break;
 	case MSR_IA32_LASTBRANCHTOIP:
-		*data = svm->vmcb->save.br_to;
+		msr_info->data = svm->vmcb->save.br_to;
 		break;
 	case MSR_IA32_LASTINTFROMIP:
-		*data = svm->vmcb->save.last_excp_from;
+		msr_info->data = svm->vmcb->save.last_excp_from;
 		break;
 	case MSR_IA32_LASTINTTOIP:
-		*data = svm->vmcb->save.last_excp_to;
+		msr_info->data = svm->vmcb->save.last_excp_to;
 		break;
 	case MSR_VM_HSAVE_PA:
-		*data = svm->nested.hsave_msr;
+		msr_info->data = svm->nested.hsave_msr;
 		break;
 	case MSR_VM_CR:
-		*data = svm->nested.vm_cr_msr;
+		msr_info->data = svm->nested.vm_cr_msr;
 		break;
 	case MSR_IA32_UCODE_REV:
-		*data = 0x01000065;
+		msr_info->data = 0x01000065;
 		break;
 	default:
-		return kvm_get_msr_common(vcpu, ecx, data);
+		return kvm_get_msr_common(vcpu, msr_info);
 	}
 	return 0;
 }
@@ -3144,16 +3144,20 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data)
 static int rdmsr_interception(struct vcpu_svm *svm)
 {
 	u32 ecx = kvm_register_read(&svm->vcpu, VCPU_REGS_RCX);
-	u64 data;
+	struct msr_data msr_info;
 
-	if (svm_get_msr(&svm->vcpu, ecx, &data)) {
+	msr_info.index = ecx;
+	msr_info.host_initiated = false;
+	if (svm_get_msr(&svm->vcpu, &msr_info)) {
 		trace_kvm_msr_read_ex(ecx);
 		kvm_inject_gp(&svm->vcpu, 0);
 	} else {
-		trace_kvm_msr_read(ecx, data);
+		trace_kvm_msr_read(ecx, msr_info.data);
 
-		kvm_register_write(&svm->vcpu, VCPU_REGS_RAX, data & 0xffffffff);
-		kvm_register_write(&svm->vcpu, VCPU_REGS_RDX, data >> 32);
+		kvm_register_write(&svm->vcpu, VCPU_REGS_RAX,
+				   msr_info.data & 0xffffffff);
+		kvm_register_write(&svm->vcpu, VCPU_REGS_RDX,
+				   msr_info.data >> 32);
 		svm->next_rip = kvm_rip_read(&svm->vcpu) + 2;
 		skip_emulated_instruction(&svm->vcpu);
 	}