KVM: x86 emulator: implement rdmsr and wrmsr

Allow real-mode emulation of rdmsr and wrmsr.  This allows smp Windows to
boot, presumably for its sipi trampoline.

Signed-off-by: Avi Kivity <avi@qumranet.com>

3 files changed, 31 insertions, 5 deletions

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 6636ae2ee3b5..3ac9cbce3369 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -569,6 +569,8 @@ void realmode_lmsw(struct kvm_vcpu *vcpu, unsigned long msw,
 unsigned long realmode_get_cr(struct kvm_vcpu *vcpu, int cr);
 void realmode_set_cr(struct kvm_vcpu *vcpu, int cr, unsigned long value,
                      unsigned long *rflags);
+int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
+int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
 
 struct x86_emulate_ctxt;
 
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 05f0418f2195..bcbe6835beb4 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1517,7 +1517,7 @@ EXPORT_SYMBOL_GPL(kvm_get_msr_common);
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
  */
-static int get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
+int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
 {
         return kvm_arch_ops->get_msr(vcpu, msr_index, pdata);
 }
@@ -1595,7 +1595,7 @@ EXPORT_SYMBOL_GPL(kvm_set_msr_common);
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
  */
-static int set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
+int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
 {
         return kvm_arch_ops->set_msr(vcpu, msr_index, data);
 }
@@ -2133,7 +2133,7 @@ static __init void kvm_init_msr_list(void)
  */
 static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data)
 {
-        return set_msr(vcpu, index, *data);
+        return kvm_set_msr(vcpu, index, *data);
 }
 
 /*
@@ -2617,7 +2617,7 @@ static long kvm_vcpu_ioctl(struct file *filp,
                 break;
         }
         case KVM_GET_MSRS:
-                r = msr_io(vcpu, argp, get_msr, 1);
+                r = msr_io(vcpu, argp, kvm_get_msr, 1);
                 break;
         case KVM_SET_MSRS:
                 r = msr_io(vcpu, argp, do_set_msr, 0);
diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index f60012d62610..1b800fc00342 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -163,7 +163,7 @@ static u16 twobyte_table[256] = {
         ModRM | ImplicitOps, ModRM, ModRM | ImplicitOps, ModRM, 0, 0, 0, 0,
         0, 0, 0, 0, 0, 0, 0, 0,
         /* 0x30 - 0x3F */
-        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        ImplicitOps, 0, ImplicitOps, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         /* 0x40 - 0x47 */
         DstReg | SrcMem | ModRM | Mov, DstReg | SrcMem | ModRM | Mov,
         DstReg | SrcMem | ModRM | Mov, DstReg | SrcMem | ModRM | Mov,
@@ -486,6 +486,7 @@ x86_emulate_memop(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
         unsigned long modrm_ea;
         int use_modrm_ea, index_reg = 0, base_reg = 0, scale, rip_relative = 0;
         int no_wb = 0;
+        u64 msr_data;
 
         /* Shadow copy of register state. Committed on successful emulation. */
         unsigned long _regs[NR_VCPU_REGS];
@@ -1344,6 +1345,29 @@ twobyte_special_insn:
                         goto cannot_emulate;
                 realmode_set_cr(ctxt->vcpu, modrm_reg, modrm_val, &_eflags);
                 break;
+        case 0x30:
+                /* wrmsr */
+                msr_data = (u32)_regs[VCPU_REGS_RAX]
+                        | ((u64)_regs[VCPU_REGS_RDX] << 32);
+                rc = kvm_set_msr(ctxt->vcpu, _regs[VCPU_REGS_RCX], msr_data);
+                if (rc) {
+                        kvm_arch_ops->inject_gp(ctxt->vcpu, 0);
+                        _eip = ctxt->vcpu->rip;
+                }
+                rc = X86EMUL_CONTINUE;
+                break;
+        case 0x32:
+                /* rdmsr */
+                rc = kvm_get_msr(ctxt->vcpu, _regs[VCPU_REGS_RCX], &msr_data);
+                if (rc) {
+                        kvm_arch_ops->inject_gp(ctxt->vcpu, 0);
+                        _eip = ctxt->vcpu->rip;
+                } else {
+                        _regs[VCPU_REGS_RAX] = (u32)msr_data;
+                        _regs[VCPU_REGS_RDX] = msr_data >> 32;
+                }
+                rc = X86EMUL_CONTINUE;
+                break;
         case 0xc7:              /* Grp9 (cmpxchg8b) */
                 {
                         u64 old, new;