LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Avi Kivity <avi@redhat.com>
To: Glauber Costa <glommer@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Rik van Riel <riel@redhat.com>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3 4/6] KVM-GST: KVM Steal time registration
Date: Tue, 15 Feb 2011 16:41:21 +0200	[thread overview]
Message-ID: <4D5A9091.6090506@redhat.com> (raw)
In-Reply-To: <1297448364-14051-5-git-send-email-glommer@redhat.com>

On 02/11/2011 08:19 PM, Glauber Costa wrote:
> Register steal time within KVM. Everytime we sample the steal time
> information, we update a local variable that tells what was the
> last time read. We then account the difference.
>
>
>
> +static int kvm_register_steal_time(void)
> +{
> +	int cpu = smp_processor_id();
> +	int low, high, ret;
> +	struct kvm_steal_time *st =&per_cpu(steal_time, cpu);
> +
> +	if (!hypervisor_steal_time)
> +		return 0;

You're using hypervisor_steal_time to communicate the existence of the 
feature.  Yuck.

> +
> +	memset(st, 0, sizeof(*st));
> +
> +	low = (int)__pa(st) | 1;

Named constant.

> +	high = ((u64)__pa(st)>>  32);
> +	ret = wrmsr_safe(MSR_KVM_STEAL_TIME, low, high);

No need for wrmsr_safe() since you're checking the cpuid bit.  The other 
APIs are nicer (no need to break into two words).

> +	printk(KERN_INFO "kvm-stealtime: cpu %d, msr %x:%x\n",
> +		cpu, high, low);
> +	return ret;
> +}
> +
>   #ifdef CONFIG_SMP
>   static void __init kvm_smp_prepare_boot_cpu(void)
>   {
>   #ifdef CONFIG_KVM_CLOCK
>   	WARN_ON(kvm_register_clock("primary cpu clock"));
>   #endif
> +	WARN_ON(kvm_register_steal_time());
>   	kvm_guest_cpu_init();
>   	native_smp_prepare_boot_cpu();
>   }
>
>   static void __cpuinit kvm_guest_cpu_online(void *dummy)
>   {
> +	WARN_ON(kvm_register_steal_time());
>   	kvm_guest_cpu_init();
>   }
>
>   static void kvm_guest_cpu_offline(void *dummy)
>   {
>   	kvm_pv_disable_apf(NULL);
> +	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);

This will trap if running on a hypervisor without this MSR.

>   	apf_task_wake_all();
>   }
>
> @@ -534,6 +557,23 @@ static void __init kvm_apf_trap_init(void)
>   	set_intr_gate(14,&async_page_fault);
>   }
>
> +static u64 kvm_account_steal_time(int cpu)
> +{
> +	u64 steal;
> +	struct kvm_steal_time *src;
> +	int version;
> +
> +	src =&per_cpu(steal_time, cpu);
> +	do {
> +		version = src->version;
> +		rmb();
> +		steal = src->steal;
> +		rmb();
> +	} while ((src->version&  1) || (version != src->version));

Check version & 1 instead of src->version & 1, slightly cheaper.

> +
> +	return steal;
> +}
> +
>
> index f98d3ea..dcb6a67 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -164,6 +164,7 @@ static void __cpuinit kvm_setup_secondary_clock(void)
>   static void kvm_crash_shutdown(struct pt_regs *regs)
>   {
>   	native_write_msr(msr_kvm_system_time, 0, 0);
> +	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
>   	native_machine_crash_shutdown(regs);
>   }

Make conditional.  Needed for the previous wrmsr as well.

>   #endif
> @@ -171,6 +172,7 @@ static void kvm_crash_shutdown(struct pt_regs *regs)
>   static void kvm_shutdown(void)
>   {
>   	native_write_msr(msr_kvm_system_time, 0, 0);
> +	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
>   	native_machine_shutdown();
>   }
>

Ditto.  Is it me, or is the code duplicated?

-- 
error compiling committee.c: too many arguments to function


  reply	other threads:[~2011-02-15 14:41 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-11 18:19 [PATCH v3 0/6] Steal time for KVM Glauber Costa
2011-02-11 18:19 ` [PATCH v3 1/6] KVM-HDR: KVM Steal time implementation Glauber Costa
2011-02-15 14:25   ` Avi Kivity
2011-02-11 18:19 ` [PATCH v3 2/6] KVM-HV: " Glauber Costa
2011-02-15 14:34   ` Avi Kivity
2011-02-11 18:19 ` [PATCH v3 3/6] KVM-GST: KVM Steal time accounting Glauber Costa
2011-02-11 19:05   ` Peter Zijlstra
2011-02-12 23:46     ` Glauber Costa
2011-02-15 14:35   ` Avi Kivity
2011-02-15 14:45     ` Peter Zijlstra
2011-02-15 15:17       ` Avi Kivity
2011-02-15 15:24         ` Rik van Riel
2011-02-15 15:26           ` Avi Kivity
2011-02-15 15:27         ` Peter Zijlstra
2011-02-11 18:19 ` [PATCH v3 4/6] KVM-GST: KVM Steal time registration Glauber Costa
2011-02-15 14:41   ` Avi Kivity [this message]
2011-02-15 15:48     ` Peter Zijlstra
2011-02-11 18:19 ` [PATCH v3 5/6] KVM-GST: adjust scheduler cpu power Glauber Costa
2011-02-11 19:05   ` Peter Zijlstra
2011-02-11 18:19 ` [PATCH v3 6/6] Describe KVM_MSR_STEAL_TIME Glauber Costa

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4D5A9091.6090506@redhat.com \
    --to=avi@redhat.com \
    --cc=glommer@redhat.com \
    --cc=jeremy.fitzhardinge@citrix.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=peterz@infradead.org \
    --cc=riel@redhat.com \
    --subject='Re: [PATCH v3 4/6] KVM-GST: KVM Steal time registration' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).