qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH 2/2] Expose tsc deadline timer cpuid to guest


From: Liu, Jinsong
Subject: Re: [Qemu-devel] [PATCH 2/2] Expose tsc deadline timer cpuid to guest
Date: Tue, 6 Mar 2012 07:49:44 +0000

Jan,

Any comments? I feel some confused about your point 'disable cpuid feature for 
older machine types by default': are you planning a common approach for this 
common issue, or, you just ask me a specific solution for the tsc deadline 
timer case?

Thanks,
Jinsong


Liu, Jinsong wrote:
>> My point is that
>> 
>>   qemu-version-A [-cpu whatever]
>> 
>> should provide the same VM as
>> 
>>   qemu-version-B -machine pc-A [-cpu whatever]
>> 
>> specifically if you leave out the cpu specification.
>> 
>> So the compat machine could establish a feature mask (e.g. append
>> some "-tsc_deadline" in this case). But, indeed, we need a new
>> channel for this. 
>> 
> 
> Yes, if such requirement need to be satisfied, I agree we need a new
> channel to solve this kind of common issue. 
> 
> As for tsc deadline timer feature exposing, I write an updated patch
> as attached. 1). It exposes tsc deadline timer feature to guest if
> in-kernel irqchip is used and kvm has emulated tsc deadline timer;
> 2). It also authorizes user to control the feature exposing via a cpu
> feature flag;  
> 
> Thanks,
> Jinsong
> 
> ====================
> From 5b7d5f459b621686e78e437010ce34748bcb9e8e Mon Sep 17 00:00:00 2001
> From: Liu, Jinsong <address@hidden>
> Date: Wed, 29 Feb 2012 01:53:15 +0800
> Subject: [PATCH] Expose tsc deadline timer feature to guest
> 
> It exposes tsc deadline timer feature to guest if in-kernel irqchip
> is used 
> and kvm has emulated tsc deadline timer.
> It also authorizes user to control the feature exposing via a cpu
> feature flag. 
> 
> Signed-off-by: Liu, Jinsong <address@hidden>
> ---
>  target-i386/cpu.h   |    1 +
>  target-i386/cpuid.c |    2 +-
>  target-i386/kvm.c   |    4 ++++
>  3 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index d92be5d..3409afe 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -399,6 +399,7 @@
>  #define CPUID_EXT_X2APIC   (1 << 21)
>  #define CPUID_EXT_MOVBE    (1 << 22)
>  #define CPUID_EXT_POPCNT   (1 << 23)
> +#define CPUID_EXT_TSC_DEADLINE_TIMER (1 << 24)
>  #define CPUID_EXT_XSAVE    (1 << 26)
>  #define CPUID_EXT_OSXSAVE  (1 << 27)
>  #define CPUID_EXT_HYPERVISOR  (1 << 31)
> diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c
> index b9bfeaf..ac4b79c 100644
> --- a/target-i386/cpuid.c
> +++ b/target-i386/cpuid.c
> @@ -50,7 +50,7 @@ static const char *ext_feature_name[] = {
>      "fma", "cx16", "xtpr", "pdcm",
>      NULL, NULL, "dca", "sse4.1|sse4_1",
>      "sse4.2|sse4_2", "x2apic", "movbe", "popcnt",
> -    NULL, "aes", "xsave", "osxsave",
> +    "tsc_deadline", "aes", "xsave", "osxsave",
>      "avx", NULL, NULL, "hypervisor",
>  };
>  static const char *ext2_feature_name[] = {
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index 7079e87..2639699 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -370,6 +370,10 @@ int kvm_arch_init_vcpu(CPUState *env)
>      i = env->cpuid_ext_features & CPUID_EXT_HYPERVISOR;
>      env->cpuid_ext_features &= kvm_arch_get_supported_cpuid(s, 1, 0,
>      R_ECX); env->cpuid_ext_features |= i;
> +    if (!kvm_irqchip_in_kernel() ||
> +        !kvm_check_extension(s, KVM_CAP_TSC_DEADLINE_TIMER)) {
> +        env->cpuid_ext_features &= ~CPUID_EXT_TSC_DEADLINE_TIMER;
> +    }
> 
>      env->cpuid_ext2_features &= kvm_arch_get_supported_cpuid(s,
>                                                              
> 0x80000001, 0, R_EDX); 




reply via email to

[Prev in Thread] Current Thread [Next in Thread]