DEFINE_PER_CPU(struct svm_cpu_data *, svm_data);
+/*
+ * Only MSR_TSC_AUX is switched via the user return hook. EFER is switched via
+ * the VMCB, and the SYSCALL/SYSENTER MSRs are handled by VMLOAD/VMSAVE.
+ *
+ * RDTSCP and RDPID are not used in the kernel, specifically to allow KVM to
+ * defer the restoration of TSC_AUX until the CPU returns to userspace.
+ */
+#define TSC_AUX_URET_SLOT 0
+
static const u32 msrpm_ranges[] = {0, 0xc0000000, 0xc0010000};
#define NUM_MSR_MAPS ARRAY_SIZE(msrpm_ranges)
kvm_tsc_scaling_ratio_frac_bits = 32;
}
+ if (boot_cpu_has(X86_FEATURE_RDTSCP))
+ kvm_define_user_return_msr(TSC_AUX_URET_SLOT, MSR_TSC_AUX);
+
/* Check for pause filtering support */
if (!boot_cpu_has(X86_FEATURE_PAUSEFILTER)) {
pause_filter_count = 0;
{
struct vcpu_svm *svm = to_svm(vcpu);
struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu);
- unsigned int i;
if (svm->guest_state_loaded)
return;
/*
- * Certain MSRs are restored on VMEXIT (sev-es), or vmload of host save
- * area (non-sev-es). Save ones that aren't so we can restore them
- * individually later.
- */
- for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
- rdmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
-
- /*
* Save additional host state that will be restored on VMEXIT (sev-es)
* or subsequent vmload of host save area.
*/
}
}
- /* This assumes that the kernel never uses MSR_TSC_AUX */
if (static_cpu_has(X86_FEATURE_RDTSCP))
- wrmsrl(MSR_TSC_AUX, svm->tsc_aux);
+ kvm_set_user_return_msr(TSC_AUX_URET_SLOT, svm->tsc_aux, -1ull);
svm->guest_state_loaded = true;
}
static void svm_prepare_host_switch(struct kvm_vcpu *vcpu)
{
- struct vcpu_svm *svm = to_svm(vcpu);
- unsigned int i;
-
- if (!svm->guest_state_loaded)
- return;
-
- /*
- * Certain MSRs are restored on VMEXIT (sev-es), or vmload of host save
- * area (non-sev-es). Restore the ones that weren't.
- */
- for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
- wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
-
- svm->guest_state_loaded = false;
+ to_svm(vcpu)->guest_state_loaded = false;
}
static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
{
struct vcpu_svm *svm = to_svm(vcpu);
+ int r;
u32 ecx = msr->index;
u64 data = msr->data;
data = (u32)data;
/*
- * This is rare, so we update the MSR here instead of using
- * direct_access_msrs. Doing that would require a rdmsr in
- * svm_vcpu_put.
+ * TSC_AUX is usually changed only during boot and never read
+ * directly. Intercept TSC_AUX instead of exposing it to the
+ * guest via direct_access_msrs, and switch it via user return.
*/
- wrmsrl(MSR_TSC_AUX, data);
+ preempt_disable();
+ r = kvm_set_user_return_msr(TSC_AUX_URET_SLOT, data, -1ull);
+ preempt_enable();
+ if (r)
+ return 1;
+
svm->tsc_aux = data;
break;
case MSR_IA32_DEBUGCTLMSR: