Re: [PATCH 3/6] KVM: X86: Make tsc_delta calculation a function of guest tsc

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-04-18 10:03, Roedel, Joerg wrote:
> On Sat, Apr 16, 2011 at 12:09:17PM -0400, Jan Kiszka wrote:
>> This patch appears to cause troubles to Linux guests on TSC clocksource
>> and APIC highres timer. The first boot after qemu start is always fine,
>> but after a reboot the guest timer appears to fire incorrectly or even
>> not at all.
> 
> Hi Jan,
> 
> can you please test if this patch fixes the problem?
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index bd57639..d7282ef 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -391,7 +391,6 @@ struct kvm_vcpu_arch {
>  	unsigned int hw_tsc_khz;
>  	unsigned int time_offset;
>  	struct page *time_page;
> -	u64 last_host_tsc;
>  	u64 last_guest_tsc;
>  	u64 last_kernel_ns;
>  	u64 last_tsc_nsec;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 1d5a7f4..d8277aa 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2146,7 +2146,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
>  {
>  	kvm_x86_ops->vcpu_put(vcpu);
>  	kvm_put_guest_fpu(vcpu);
> -	vcpu->arch.last_host_tsc = native_read_tsc();
> +	kvm_get_msr(vcpu, MSR_IA32_TSC, &vcpu->arch.last_guest_tsc);
>  }
>  
>  static int is_efer_nx(void)
> 

Looks good, behaviour is now fine also after reboot.

Thanks,
Jan

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