Re: [Qemu-devel] [PATCH 2/2] Qemu co-operation with kvm tsc deadline timer

[Jan Kiszka]

On 2011-09-13 16:38, Liu, Jinsong wrote:
> From c1b502d6548fcc41592cd90acc82109ee949df75 Mon Sep 17 00:00:00 2001
> From: Liu, Jinsong <address@hidden>
> Date: Tue, 13 Sep 2011 22:05:30 +0800
> Subject: [PATCH] Qemu co-operation with kvm tsc deadline timer
> 
> KVM add emulation of lapic tsc deadline timer for guest.
> This patch is co-operation work at qemu side.
> 
> Signed-off-by: Liu, Jinsong <address@hidden>
> ---
>  target-i386/cpu.h |    2 ++
>  target-i386/kvm.c |   14 ++++++++++++++
>  2 files changed, 16 insertions(+), 0 deletions(-)
> 
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index 935d08a..62ff73c 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -283,6 +283,7 @@
>  #define MSR_IA32_APICBASE_BSP           (1<<8)
>  #define MSR_IA32_APICBASE_ENABLE        (1<<11)
>  #define MSR_IA32_APICBASE_BASE          (0xfffff<<12)
> +#define MSR_IA32_TSCDEADLINE            0x6e0
>  
>  #define MSR_MTRRcap                  0xfe
>  #define MSR_MTRRcap_VCNT             8
> @@ -687,6 +688,7 @@ typedef struct CPUX86State {
>      uint64_t async_pf_en_msr;
>  
>      uint64_t tsc;
> +    uint64_t tsc_deadline;

This field has to be saved/restored for snapshots/migrations.

Frankly, I've no clue right now if substates are in vogue again (they
had problems in their binary format) or if you can simply add a
versioned top-level field and bump the CPUState version number.

>  
>      uint64_t mcg_status;
>  
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index aa843f0..206fcad 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -59,6 +59,7 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
>  
>  static bool has_msr_star;
>  static bool has_msr_hsave_pa;
> +static bool has_msr_tsc_deadline;
>  static bool has_msr_async_pf_en;
>  static int lm_capable_kernel;
>  
> @@ -571,6 +572,10 @@ static int kvm_get_supported_msrs(KVMState *s)
>                      has_msr_hsave_pa = true;
>                      continue;
>                  }
> +                if (kvm_msr_list->indices[i] == MSR_IA32_TSCDEADLINE) {
> +                    has_msr_tsc_deadline = true;
> +                    continue;
> +                }
>              }
>          }
>  
> @@ -899,6 +904,9 @@ static int kvm_put_msrs(CPUState *env, int level)
>      if (has_msr_hsave_pa) {
>          kvm_msr_entry_set(&msrs[n++], MSR_VM_HSAVE_PA, env->vm_hsave);
>      }
> +    if (has_msr_tsc_deadline) {
> +        kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSCDEADLINE, 
> env->tsc_deadline);
> +    }
>  #ifdef TARGET_X86_64
>      if (lm_capable_kernel) {
>          kvm_msr_entry_set(&msrs[n++], MSR_CSTAR, env->cstar);
> @@ -1145,6 +1153,9 @@ static int kvm_get_msrs(CPUState *env)
>      if (has_msr_hsave_pa) {
>          msrs[n++].index = MSR_VM_HSAVE_PA;
>      }
> +    if (has_msr_tsc_deadline) {
> +        msrs[n++].index = MSR_IA32_TSCDEADLINE;
> +    }
>  
>      if (!env->tsc_valid) {
>          msrs[n++].index = MSR_IA32_TSC;
> @@ -1213,6 +1224,9 @@ static int kvm_get_msrs(CPUState *env)
>          case MSR_IA32_TSC:
>              env->tsc = msrs[i].data;
>              break;
> +        case MSR_IA32_TSCDEADLINE:
> +            env->tsc_deadline = msrs[i].data;
> +            break;
>          case MSR_VM_HSAVE_PA:
>              env->vm_hsave = msrs[i].data;
>              break;

Just to double check: This feature is exposed to the guest when A) the
host CPU supports it and B) QEMU passed down guest CPU specifications
(cpuid data) that allow it as well?

Jan

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