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[Qemu-devel] [PATCH v6 2/3] target-i386: reorganize TSC rate setting cod
From: |
Haozhong Zhang |
Subject: |
[Qemu-devel] [PATCH v6 2/3] target-i386: reorganize TSC rate setting code |
Date: |
Tue, 24 Nov 2015 11:33:56 +0800 |
Following changes are made to the TSC rate setting code in
kvm_arch_init_vcpu():
* The code is moved to a new function kvm_arch_set_tsc_khz().
* If kvm_arch_set_tsc_khz() fails, i.e. following two conditions are
both satisfied:
* KVM does not support the TSC scaling or it fails to set vcpu's
TSC rate by KVM_SET_TSC_KHZ,
* the TSC rate to be set is different than the value currently used
by KVM,
then kvm_arch_init_vcpu() will fail. Prevously,
* the lack of TSC scaling never failed kvm_arch_init_vcpu(),
* the failure of KVM_SET_TSC_KHZ failed kvm_arch_init_vcpu()
unconditionally, even though the TSC rate to be set is identical
to the value currently used by KVM.
Signed-off-by: Haozhong Zhang <address@hidden>
---
target-i386/kvm.c | 40 +++++++++++++++++++++++++++++++++-------
1 file changed, 33 insertions(+), 7 deletions(-)
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index a0fe9d4..1e811ee 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -524,6 +524,36 @@ static bool hyperv_enabled(X86CPU *cpu)
cpu->hyperv_runtime);
}
+static int kvm_arch_set_tsc_khz(CPUState *cs)
+{
+ X86CPU *cpu = X86_CPU(cs);
+ CPUX86State *env = &cpu->env;
+ int r;
+
+ if (!env->tsc_khz) {
+ return 0;
+ }
+
+ r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL) ?
+ kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz) :
+ -ENOTSUP;
+ if (r < 0) {
+ /* When KVM_SET_TSC_KHZ fails, it's an error only if the current
+ * TSC frequency doesn't match the one we want.
+ */
+ int cur_freq = kvm_check_extension(cs->kvm_state, KVM_CAP_GET_TSC_KHZ)
?
+ kvm_vcpu_ioctl(cs, KVM_GET_TSC_KHZ) :
+ -ENOTSUP;
+ if (cur_freq <= 0 || cur_freq != env->tsc_khz) {
+ error_report("warning: TSC frequency mismatch between "
+ "VM and host, and TSC scaling unavailable");
+ return r;
+ }
+ }
+
+ return 0;
+}
+
static Error *invtsc_mig_blocker;
#define KVM_MAX_CPUID_ENTRIES 100
@@ -823,13 +853,9 @@ int kvm_arch_init_vcpu(CPUState *cs)
return r;
}
- r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL);
- if (r && env->tsc_khz) {
- r = kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz);
- if (r < 0) {
- fprintf(stderr, "KVM_SET_TSC_KHZ failed\n");
- return r;
- }
+ r = kvm_arch_set_tsc_khz(cs);
+ if (r < 0) {
+ return r;
}
/* vcpu's TSC frequency is either specified by user, or following
--
2.4.8