* [PATCH] kvm: disable stealtime via reboot notifier to avoid mem corruption
@ 2012-08-10 10:36 Florian Westphal
2012-08-13 21:52 ` Marcelo Tosatti
0 siblings, 1 reply; 4+ messages in thread
From: Florian Westphal @ 2012-08-10 10:36 UTC (permalink / raw)
To: kvm; +Cc: avi, linux-kernel, Florian Westphal
else, we get memory corruption on reboot; found when tracking down
initramfs unpack error on initial reboot (with qemu-kvm -smp 2,
no problem with single-core).
problem with doing it via kvm_shutdown() is that this file
depends on CONFIG_KVM_CLOCK, also its not enough to call it for one
cpu only.
Signed-off-by: Florian Westphal <fw@strlen.de>
---
not subscribed, please CC on replies.
Also, I don't know much about kvm or kexec, so its possible
that i missed something.
In any case, this seems to fix the initramfs corruption for me.
patch is against virt/kvm/kvm.git.
arch/x86/kernel/kvm.c | 1 +
arch/x86/kernel/kvmclock.c | 1 -
2 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index c1d61ee..1596cc8 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -354,6 +354,7 @@ static void kvm_pv_guest_cpu_reboot(void *unused)
if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
wrmsrl(MSR_KVM_PV_EOI_EN, 0);
kvm_pv_disable_apf();
+ kvm_disable_steal_time();
}
static int kvm_pv_reboot_notify(struct notifier_block *nb,
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index f1b42b3..5a2fa7d 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -191,7 +191,6 @@ static void kvm_crash_shutdown(struct pt_regs *regs)
static void kvm_shutdown(void)
{
native_write_msr(msr_kvm_system_time, 0, 0);
- kvm_disable_steal_time();
native_machine_shutdown();
}
--
1.7.8.6
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] kvm: disable stealtime via reboot notifier to avoid mem corruption
2012-08-10 10:36 [PATCH] kvm: disable stealtime via reboot notifier to avoid mem corruption Florian Westphal
@ 2012-08-13 21:52 ` Marcelo Tosatti
2012-08-14 9:15 ` Florian Westphal
0 siblings, 1 reply; 4+ messages in thread
From: Marcelo Tosatti @ 2012-08-13 21:52 UTC (permalink / raw)
To: Florian Westphal; +Cc: kvm, avi, linux-kernel
On Fri, Aug 10, 2012 at 12:36:22PM +0200, Florian Westphal wrote:
> else, we get memory corruption on reboot; found when tracking down
> initramfs unpack error on initial reboot (with qemu-kvm -smp 2,
> no problem with single-core).
>
> problem with doing it via kvm_shutdown() is that this file
> depends on CONFIG_KVM_CLOCK, also its not enough to call it for one
> cpu only.
>
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
> not subscribed, please CC on replies.
> Also, I don't know much about kvm or kexec, so its possible
> that i missed something.
>
> In any case, this seems to fix the initramfs corruption for me.
> patch is against virt/kvm/kvm.git.
>
> arch/x86/kernel/kvm.c | 1 +
> arch/x86/kernel/kvmclock.c | 1 -
> 2 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index c1d61ee..1596cc8 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -354,6 +354,7 @@ static void kvm_pv_guest_cpu_reboot(void *unused)
> if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
> wrmsrl(MSR_KVM_PV_EOI_EN, 0);
> kvm_pv_disable_apf();
> + kvm_disable_steal_time();
> }
>
> static int kvm_pv_reboot_notify(struct notifier_block *nb,
This part below will introduce a bug for shutdown. Can you retest with
the addition of kvm_disable_steal_time to kvm_pv_guest_cpu_reboot only,
retest and resend please?
Thanks
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index f1b42b3..5a2fa7d 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -191,7 +191,6 @@ static void kvm_crash_shutdown(struct pt_regs *regs)
> static void kvm_shutdown(void)
> {
> native_write_msr(msr_kvm_system_time, 0, 0);
> - kvm_disable_steal_time();
> native_machine_shutdown();
> }
>
> --
> 1.7.8.6
>
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] kvm: disable stealtime via reboot notifier to avoid mem corruption
2012-08-13 21:52 ` Marcelo Tosatti
@ 2012-08-14 9:15 ` Florian Westphal
2012-08-14 15:32 ` Marcelo Tosatti
0 siblings, 1 reply; 4+ messages in thread
From: Florian Westphal @ 2012-08-14 9:15 UTC (permalink / raw)
To: Marcelo Tosatti; +Cc: Florian Westphal, kvm, avi, linux-kernel
Marcelo Tosatti <mtosatti@redhat.com> wrote:
> On Fri, Aug 10, 2012 at 12:36:22PM +0200, Florian Westphal wrote:
> > --- a/arch/x86/kernel/kvmclock.c
> > +++ b/arch/x86/kernel/kvmclock.c
> > @@ -191,7 +191,6 @@ static void kvm_crash_shutdown(struct pt_regs *regs)
> > static void kvm_shutdown(void)
> > {
> > native_write_msr(msr_kvm_system_time, 0, 0);
> > - kvm_disable_steal_time();
> > native_machine_shutdown();
> > }
> This part below will introduce a bug for shutdown. Can you retest with
> the addition of kvm_disable_steal_time to kvm_pv_guest_cpu_reboot only,
> retest and resend please?
I can, but the problem with kvm_disable_steal_time() in
kvmclock.c is that with CONFIG_KVM_CLOCK=n the entire
file won't be compiled.
And steal time doesn't depend on CONFIG_KVM_CLOCK=y.
So if removing it there is a bug leaving it in only avoids
that bug for CONFIG_KVM_CLOCK=y.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] kvm: disable stealtime via reboot notifier to avoid mem corruption
2012-08-14 9:15 ` Florian Westphal
@ 2012-08-14 15:32 ` Marcelo Tosatti
0 siblings, 0 replies; 4+ messages in thread
From: Marcelo Tosatti @ 2012-08-14 15:32 UTC (permalink / raw)
To: Florian Westphal; +Cc: kvm, avi, linux-kernel
On Tue, Aug 14, 2012 at 11:15:06AM +0200, Florian Westphal wrote:
> Marcelo Tosatti <mtosatti@redhat.com> wrote:
> > On Fri, Aug 10, 2012 at 12:36:22PM +0200, Florian Westphal wrote:
> > > --- a/arch/x86/kernel/kvmclock.c
> > > +++ b/arch/x86/kernel/kvmclock.c
> > > @@ -191,7 +191,6 @@ static void kvm_crash_shutdown(struct pt_regs *regs)
> > > static void kvm_shutdown(void)
> > > {
> > > native_write_msr(msr_kvm_system_time, 0, 0);
> > > - kvm_disable_steal_time();
> > > native_machine_shutdown();
> > > }
> > This part below will introduce a bug for shutdown. Can you retest with
> > the addition of kvm_disable_steal_time to kvm_pv_guest_cpu_reboot only,
> > retest and resend please?
>
> I can, but the problem with kvm_disable_steal_time() in
> kvmclock.c is that with CONFIG_KVM_CLOCK=n the entire
> file won't be compiled.
>
> And steal time doesn't depend on CONFIG_KVM_CLOCK=y.
> So if removing it there is a bug leaving it in only avoids
> that bug for CONFIG_KVM_CLOCK=y.
I meant to add kvm_disable_steal_time() call to arch/x86/kernel/kvm.c,
the first part of your patch, here:
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index c1d61ee..1596cc8 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -354,6 +354,7 @@ static void kvm_pv_guest_cpu_reboot(void *unused)
if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
wrmsrl(MSR_KVM_PV_EOI_EN, 0);
kvm_pv_disable_apf();
+ kvm_disable_steal_time();
}
static int kvm_pv_reboot_notify(struct notifier_block *nb,
Can you test only that part and resend?
The call to kvm_disable_steal_time() in kvmclock.c should not be
removed.
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-08-14 15:37 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2012-08-10 10:36 [PATCH] kvm: disable stealtime via reboot notifier to avoid mem corruption Florian Westphal
2012-08-13 21:52 ` Marcelo Tosatti
2012-08-14 9:15 ` Florian Westphal
2012-08-14 15:32 ` Marcelo Tosatti
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