[PATCH 21/27] target/i386/mshv: Write MSRs to the hypervisor

[Paolo Bonzini <pbonzini@redhat.com>]

From: Magnus Kulke <magnuskulke@linux.microsoft.com>

Push current model-specific register (MSR) values to MSHV's vCPUs as
part of setting state to the hypervisor.

Signed-off-by: Magnus Kulke <magnuskulke@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250916164847.77883-22-magnuskulke@linux.microsoft.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/mshv/mshv-cpu.c | 68 +++++++++++++++++++++++++++++++++++--
 1 file changed, 66 insertions(+), 2 deletions(-)

diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c
index 424ebdb1228..33a3ce8b110 100644
--- a/target/i386/mshv/mshv-cpu.c
+++ b/target/i386/mshv/mshv-cpu.c
@@ -998,6 +998,65 @@ static int put_regs(const CPUState *cpu)
     return 0;
 }
 
+struct MsrPair {
+    uint32_t index;
+    uint64_t value;
+};
+
+static int put_msrs(const CPUState *cpu)
+{
+    int ret = 0;
+    X86CPU *x86cpu = X86_CPU(cpu);
+    CPUX86State *env = &x86cpu->env;
+    MshvMsrEntries *msrs = g_malloc0(sizeof(MshvMsrEntries));
+
+    struct MsrPair pairs[] = {
+        { MSR_IA32_SYSENTER_CS,    env->sysenter_cs },
+        { MSR_IA32_SYSENTER_ESP,   env->sysenter_esp },
+        { MSR_IA32_SYSENTER_EIP,   env->sysenter_eip },
+        { MSR_EFER,                env->efer },
+        { MSR_PAT,                 env->pat },
+        { MSR_STAR,                env->star },
+        { MSR_CSTAR,               env->cstar },
+        { MSR_LSTAR,               env->lstar },
+        { MSR_KERNELGSBASE,        env->kernelgsbase },
+        { MSR_FMASK,               env->fmask },
+        { MSR_MTRRdefType,         env->mtrr_deftype },
+        { MSR_VM_HSAVE_PA,         env->vm_hsave },
+        { MSR_SMI_COUNT,           env->msr_smi_count },
+        { MSR_IA32_PKRS,           env->pkrs },
+        { MSR_IA32_BNDCFGS,        env->msr_bndcfgs },
+        { MSR_IA32_XSS,            env->xss },
+        { MSR_IA32_UMWAIT_CONTROL, env->umwait },
+        { MSR_IA32_TSX_CTRL,       env->tsx_ctrl },
+        { MSR_AMD64_TSC_RATIO,     env->amd_tsc_scale_msr },
+        { MSR_TSC_AUX,             env->tsc_aux },
+        { MSR_TSC_ADJUST,          env->tsc_adjust },
+        { MSR_IA32_SMBASE,         env->smbase },
+        { MSR_IA32_SPEC_CTRL,      env->spec_ctrl },
+        { MSR_VIRT_SSBD,           env->virt_ssbd },
+    };
+
+    if (ARRAY_SIZE(pairs) > MSHV_MSR_ENTRIES_COUNT) {
+        error_report("MSR entries exceed maximum size");
+        g_free(msrs);
+        return -1;
+    }
+
+    for (size_t i = 0; i < ARRAY_SIZE(pairs); i++) {
+        MshvMsrEntry *entry = &msrs->entries[i];
+        entry->index = pairs[i].index;
+        entry->reserved = 0;
+        entry->data = pairs[i].value;
+        msrs->nmsrs++;
+    }
+
+    ret = mshv_configure_msr(cpu, &msrs->entries[0], msrs->nmsrs);
+    g_free(msrs);
+    return ret;
+}
+
+
 int mshv_arch_put_registers(const CPUState *cpu)
 {
     int ret;
@@ -1008,8 +1067,13 @@ int mshv_arch_put_registers(const CPUState *cpu)
         return -1;
     }
 
-    error_report("unimplemented");
-    abort();
+    ret = put_msrs(cpu);
+    if (ret < 0) {
+        error_report("Failed to put msrs");
+        return -1;
+    }
+
+    return 0;
 }
 
 void mshv_arch_amend_proc_features(
-- 
2.51.0