KVM: Implement bare minimum of HYPER-V MSRs

Minimum HYPER-V implementation should have GUEST_OS_ID, HYPERCALL and
VP_INDEX MSRs.

[avi: fix build on i386]

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Vadim Rozenfeld <vrozenfe@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 192 insertions, 1 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1ad34d185da9..480137db4770 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -622,9 +622,10 @@ static inline u32 bit(int bitno)
  * kvm-specific. Those are put in the beginning of the list.
  */
 
-#define KVM_SAVE_MSRS_BEGIN     2
+#define KVM_SAVE_MSRS_BEGIN     4
 static u32 msrs_to_save[] = {
         MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK,
+        HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL,
         MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
         MSR_K6_STAR,
 #ifdef CONFIG_X86_64
@@ -1004,6 +1005,74 @@ out:
         return r;
 }
 
+static bool kvm_hv_hypercall_enabled(struct kvm *kvm)
+{
+        return kvm->arch.hv_hypercall & HV_X64_MSR_HYPERCALL_ENABLE;
+}
+
+static bool kvm_hv_msr_partition_wide(u32 msr)
+{
+        bool r = false;
+        switch (msr) {
+        case HV_X64_MSR_GUEST_OS_ID:
+        case HV_X64_MSR_HYPERCALL:
+                r = true;
+                break;
+        }
+
+        return r;
+}
+
+static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+{
+        struct kvm *kvm = vcpu->kvm;
+
+        switch (msr) {
+        case HV_X64_MSR_GUEST_OS_ID:
+                kvm->arch.hv_guest_os_id = data;
+                /* setting guest os id to zero disables hypercall page */
+                if (!kvm->arch.hv_guest_os_id)
+                        kvm->arch.hv_hypercall &= ~HV_X64_MSR_HYPERCALL_ENABLE;
+                break;
+        case HV_X64_MSR_HYPERCALL: {
+                u64 gfn;
+                unsigned long addr;
+                u8 instructions[4];
+
+                /* if guest os id is not set hypercall should remain disabled */
+                if (!kvm->arch.hv_guest_os_id)
+                        break;
+                if (!(data & HV_X64_MSR_HYPERCALL_ENABLE)) {
+                        kvm->arch.hv_hypercall = data;
+                        break;
+                }
+                gfn = data >> HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT;
+                addr = gfn_to_hva(kvm, gfn);
+                if (kvm_is_error_hva(addr))
+                        return 1;
+                kvm_x86_ops->patch_hypercall(vcpu, instructions);
+                ((unsigned char *)instructions)[3] = 0xc3; /* ret */
+                if (copy_to_user((void __user *)addr, instructions, 4))
+                        return 1;
+                kvm->arch.hv_hypercall = data;
+                break;
+        }
+        default:
+                pr_unimpl(vcpu, "HYPER-V unimplemented wrmsr: 0x%x "
+                          "data 0x%llx\n", msr, data);
+                return 1;
+        }
+        return 0;
+}
+
+static int set_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+{
+        pr_unimpl(vcpu, "HYPER-V unimplemented wrmsr: 0x%x data 0x%llx\n",
+                  msr, data);
+
+        return 1;
+}
+
 int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
         switch (msr) {
@@ -1118,6 +1187,16 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
                 pr_unimpl(vcpu, "unimplemented perfctr wrmsr: "
                         "0x%x data 0x%llx\n", msr, data);
                 break;
+        case HV_X64_MSR_GUEST_OS_ID ... HV_X64_MSR_SINT15:
+                if (kvm_hv_msr_partition_wide(msr)) {
+                        int r;
+                        mutex_lock(&vcpu->kvm->lock);
+                        r = set_msr_hyperv_pw(vcpu, msr, data);
+                        mutex_unlock(&vcpu->kvm->lock);
+                        return r;
+                } else
+                        return set_msr_hyperv(vcpu, msr, data);
+                break;
         default:
                 if (msr && (msr == vcpu->kvm->arch.xen_hvm_config.msr))
                         return xen_hvm_config(vcpu, data);
@@ -1217,6 +1296,48 @@ static int get_msr_mce(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
         return 0;
 }
 
+static int get_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
+{
+        u64 data = 0;
+        struct kvm *kvm = vcpu->kvm;
+
+        switch (msr) {
+        case HV_X64_MSR_GUEST_OS_ID:
+                data = kvm->arch.hv_guest_os_id;
+                break;
+        case HV_X64_MSR_HYPERCALL:
+                data = kvm->arch.hv_hypercall;
+                break;
+        default:
+                pr_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
+                return 1;
+        }
+
+        *pdata = data;
+        return 0;
+}
+
+static int get_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
+{
+        u64 data = 0;
+
+        switch (msr) {
+        case HV_X64_MSR_VP_INDEX: {
+                int r;
+                struct kvm_vcpu *v;
+                kvm_for_each_vcpu(r, v, vcpu->kvm)
+                        if (v == vcpu)
+                                data = r;
+                break;
+        }
+        default:
+                pr_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
+                return 1;
+        }
+        *pdata = data;
+        return 0;
+}
+
 int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 {
         u64 data;
@@ -1283,6 +1404,16 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
         case MSR_IA32_MCG_STATUS:
         case MSR_IA32_MC0_CTL ... MSR_IA32_MC0_CTL + 4 * KVM_MAX_MCE_BANKS - 1:
                 return get_msr_mce(vcpu, msr, pdata);
+        case HV_X64_MSR_GUEST_OS_ID ... HV_X64_MSR_SINT15:
+                if (kvm_hv_msr_partition_wide(msr)) {
+                        int r;
+                        mutex_lock(&vcpu->kvm->lock);
+                        r = get_msr_hyperv_pw(vcpu, msr, pdata);
+                        mutex_unlock(&vcpu->kvm->lock);
+                        return r;
+                } else
+                        return get_msr_hyperv(vcpu, msr, pdata);
+                break;
         default:
                 if (!ignore_msrs) {
                         pr_unimpl(vcpu, "unhandled rdmsr: 0x%x\n", msr);
@@ -1398,6 +1529,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_XEN_HVM:
         case KVM_CAP_ADJUST_CLOCK:
         case KVM_CAP_VCPU_EVENTS:
+        case KVM_CAP_HYPERV:
                 r = 1;
                 break;
         case KVM_CAP_COALESCED_MMIO:
@@ -3618,11 +3750,70 @@ static inline gpa_t hc_gpa(struct kvm_vcpu *vcpu, unsigned long a0,
                 return a0 | ((gpa_t)a1 << 32);
 }
 
+int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
+{
+        u64 param, ingpa, outgpa, ret;
+        uint16_t code, rep_idx, rep_cnt, res = HV_STATUS_SUCCESS, rep_done = 0;
+        bool fast, longmode;
+        int cs_db, cs_l;
+
+        /*
+         * hypercall generates UD from non zero cpl and real mode
+         * per HYPER-V spec
+         */
+        if (kvm_x86_ops->get_cpl(vcpu) != 0 ||
+            !kvm_read_cr0_bits(vcpu, X86_CR0_PE)) {
+                kvm_queue_exception(vcpu, UD_VECTOR);
+                return 0;
+        }
+
+        kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
+        longmode = is_long_mode(vcpu) && cs_l == 1;
+
+        if (!longmode) {
+                param = (kvm_register_read(vcpu, VCPU_REGS_RDX) << 32) |
+                        (kvm_register_read(vcpu, VCPU_REGS_RAX) & 0xffffff);
+                ingpa = (kvm_register_read(vcpu, VCPU_REGS_RBX) << 32) |
+                        (kvm_register_read(vcpu, VCPU_REGS_RCX) & 0xffffff);
+                outgpa = (kvm_register_read(vcpu, VCPU_REGS_RDI) << 32) |
+                        (kvm_register_read(vcpu, VCPU_REGS_RSI) & 0xffffff);
+        }
+#ifdef CONFIG_X86_64
+        else {
+                param = kvm_register_read(vcpu, VCPU_REGS_RCX);
+                ingpa = kvm_register_read(vcpu, VCPU_REGS_RDX);
+                outgpa = kvm_register_read(vcpu, VCPU_REGS_R8);
+        }
+#endif
+
+        code = param & 0xffff;
+        fast = (param >> 16) & 0x1;
+        rep_cnt = (param >> 32) & 0xfff;
+        rep_idx = (param >> 48) & 0xfff;
+
+        trace_kvm_hv_hypercall(code, fast, rep_cnt, rep_idx, ingpa, outgpa);
+
+        res = HV_STATUS_INVALID_HYPERCALL_CODE;
+
+        ret = res | (((u64)rep_done & 0xfff) << 32);
+        if (longmode) {
+                kvm_register_write(vcpu, VCPU_REGS_RAX, ret);
+        } else {
+                kvm_register_write(vcpu, VCPU_REGS_RDX, ret >> 32);
+                kvm_register_write(vcpu, VCPU_REGS_RAX, ret & 0xffffffff);
+        }
+
+        return 1;
+}
+
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 {
         unsigned long nr, a0, a1, a2, a3, ret;
         int r = 1;
 
+        if (kvm_hv_hypercall_enabled(vcpu->kvm))
+                return kvm_hv_hypercall(vcpu);
+
         nr = kvm_register_read(vcpu, VCPU_REGS_RAX);
         a0 = kvm_register_read(vcpu, VCPU_REGS_RBX);
         a1 = kvm_register_read(vcpu, VCPU_REGS_RCX);