| Message ID | 1446106927-15490-2-git-send-email-liang.z.li@intel.com |
|---|---|
| State | New |
| Headers | show |
On 29/10/2015 09:22, Liang Li wrote: > +int kvm_get_tsc(CPUState *cs) > +{ > + X86CPU *cpu = X86_CPU(cs); > + CPUX86State *env = &cpu->env; > + struct { > + struct kvm_msrs info; > + struct kvm_msr_entry entries[1]; > + } msr_data; > + struct kvm_msr_entry *msrs = msr_data.entries; > + int ret, i, n; > + > + n = 0; > + > + if (!env->tsc_valid) { > + msrs[n++].index = MSR_IA32_TSC; > + env->tsc_valid = !runstate_is_running(); > + } > + > + if (n == 0) { > + return 0; > + } > + > + msr_data.info = (struct kvm_msrs) { > + .nmsrs = n, > + }; > + > + ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, &msr_data); > + if (ret < 0) { > + return ret; > + } > + > + for (i = 0; i < ret; i++) { > + uint32_t index = msrs[i].index; > + switch (index) { > + case MSR_IA32_TSC: > + env->tsc = msrs[i].data; > + break; > + default: > + break; > + } > + } > + > + return 0; > +} > + > + This can be simplified a bit: int kvm_get_tsc(CPUState *cs) { X86CPU *cpu = X86_CPU(cs); CPUX86State *env = &cpu->env; struct { struct kvm_msrs info; struct kvm_msr_entry entries[1]; } msr_data; int ret; if (env->tsc_valid) { return 0; } msr_data.info.nmsrs = 1; msr_data.entries[0].index = MSR_IA32_TSC; env->tsc_valid = !runstate_is_running(); ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, &msr_data); if (ret < 0) { return ret; } env->tsc = msr_data.entries[0].data; return 0; } > > + CPU_FOREACH(cpu) { > + ret = kvm_get_tsc(cpu); > + if (ret < 0) { > + fprintf(stderr, "KVM_GET_MSRS failed: %s\n", strerror(ret)); > + abort(); > + return; > + } > + } This should be run in the appropriate thread using run_on_cpu. VCPU ioctls should only be invoked from the VCPU thread. So you should introduce a new function kvm_synchronize_all_tsc() or something like that. Otherwise, the idea behind the patches is fine. Thanks! Paolo
> This can be simplified a bit: > > int kvm_get_tsc(CPUState *cs) > { > X86CPU *cpu = X86_CPU(cs); > CPUX86State *env = &cpu->env; > struct { > struct kvm_msrs info; > struct kvm_msr_entry entries[1]; > } msr_data; > int ret; > > if (env->tsc_valid) { > return 0; > } > > msr_data.info.nmsrs = 1; > msr_data.entries[0].index = MSR_IA32_TSC; > env->tsc_valid = !runstate_is_running(); > > ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, &msr_data); > if (ret < 0) { > return ret; > } > > env->tsc = msr_data.entries[0].data; > return 0; > } > > > > > + CPU_FOREACH(cpu) { > > + ret = kvm_get_tsc(cpu); > > + if (ret < 0) { > > + fprintf(stderr, "KVM_GET_MSRS failed: %s\n", strerror(ret)); > > + abort(); > > + return; > > + } > > + } > > > This should be run in the appropriate thread using run_on_cpu. VCPU ioctls > should only be invoked from the VCPU thread. So you should introduce a new > function kvm_synchronize_all_tsc() or something like that. > > Otherwise, the idea behind the patches is fine. Thanks! > > Paolo Thanks for your comments, I will send the v3. Liang
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index efdf165..2e69cdb 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -17,7 +17,7 @@ #include "qemu/host-utils.h" #include "sysemu/sysemu.h" #include "sysemu/kvm.h" -#include "sysemu/cpus.h" +#include "kvm_i386.h" #include "hw/sysbus.h" #include "hw/kvm/clock.h" @@ -125,22 +125,14 @@ static void kvmclock_vm_state_change(void *opaque, int running, return; } - cpu_synchronize_all_states(); - /* In theory, the cpu_synchronize_all_states() call above wouldn't - * affect the rest of the code, as the VCPU state inside CPUState - * is supposed to always match the VCPU state on the kernel side. - * - * In practice, calling cpu_synchronize_state() too soon will load the - * kernel-side APIC state into X86CPU.apic_state too early, APIC state - * won't be reloaded later because CPUState.vcpu_dirty==true, and - * outdated APIC state may be migrated to another host. - * - * The real fix would be to make sure outdated APIC state is read - * from the kernel again when necessary. While this is not fixed, we - * need the cpu_clean_all_dirty() call below. - */ - cpu_clean_all_dirty(); - + CPU_FOREACH(cpu) { + ret = kvm_get_tsc(cpu); + if (ret < 0) { + fprintf(stderr, "KVM_GET_MSRS failed: %s\n", strerror(ret)); + abort(); + return; + } + } ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data); if (ret < 0) { fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret)); diff --git a/target-i386/kvm.c b/target-i386/kvm.c index 64046cb..eae90e1 100644 --- a/target-i386/kvm.c +++ b/target-i386/kvm.c @@ -111,6 +111,52 @@ bool kvm_allows_irq0_override(void) return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing(); } +int kvm_get_tsc(CPUState *cs) +{ + X86CPU *cpu = X86_CPU(cs); + CPUX86State *env = &cpu->env; + struct { + struct kvm_msrs info; + struct kvm_msr_entry entries[1]; + } msr_data; + struct kvm_msr_entry *msrs = msr_data.entries; + int ret, i, n; + + n = 0; + + if (!env->tsc_valid) { + msrs[n++].index = MSR_IA32_TSC; + env->tsc_valid = !runstate_is_running(); + } + + if (n == 0) { + return 0; + } + + msr_data.info = (struct kvm_msrs) { + .nmsrs = n, + }; + + ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, &msr_data); + if (ret < 0) { + return ret; + } + + for (i = 0; i < ret; i++) { + uint32_t index = msrs[i].index; + switch (index) { + case MSR_IA32_TSC: + env->tsc = msrs[i].data; + break; + default: + break; + } + } + + return 0; +} + + static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max) { struct kvm_cpuid2 *cpuid; diff --git a/target-i386/kvm_i386.h b/target-i386/kvm_i386.h index e557e94..141fab5 100644 --- a/target-i386/kvm_i386.h +++ b/target-i386/kvm_i386.h @@ -17,6 +17,7 @@ bool kvm_allows_irq0_override(void); bool kvm_has_smm(void); void kvm_arch_reset_vcpu(X86CPU *cs); void kvm_arch_do_init_vcpu(X86CPU *cs); +int kvm_get_tsc(CPUState *cs); int kvm_device_pci_assign(KVMState *s, PCIHostDeviceAddress *dev_addr, uint32_t flags, uint32_t *dev_id);
The commit 317b0a6d8 fixed an issue which caused by the outdated env->tsc value, but the fix lead to cpu_synchronize_all_states called twice during live migration. The cpu_synchronize_all_states takes about 130us for a VM which has 4 vcpus, it's a bit expensive. This patch use a light weight interface to update the env->tsc value, it only takes about 20us to update the env->tsc. Signed-off-by: Liang Li <liang.z.li@intel.com> --- hw/i386/kvm/clock.c | 26 +++++++++----------------- target-i386/kvm.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ target-i386/kvm_i386.h | 1 + 3 files changed, 56 insertions(+), 17 deletions(-)