From: Paolo Bonzini <pbonzini@redhat.com>
To: Maxim Levitsky <mlevitsk@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Jim Mattson <jmattson@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Joerg Roedel <joro@8bytes.org>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v2 1/1] KVM: x86: fix MSR_IA32_TSC read for nested migration
Date: Tue, 22 Sep 2020 18:39:16 +0200 [thread overview]
Message-ID: <a0821152-19b7-9d46-aefd-759f462902b7@redhat.com> (raw)
In-Reply-To: <5d19bbf5bcc4975e4ac6c4aef8b92b4a1ed4bc16.camel@redhat.com>
On 22/09/20 17:39, Maxim Levitsky wrote:
>>> I'll talk to Maxim and see if he can work on the kvmclock migration stuff.
>
> We talked about this on IRC and now I am also convinced that we should implement
> proper TSC migration instead, so I guess I'll drop this patch and I will implement it.
>
> Last few weeks I was digging through all the timing code, and I mostly understand it
> so it shouldn't take me much time to implement it.
>
> There is hope that this will make nested migration fully stable since, with this patch,
> it still sometimes hangs. While on my AMD machine it takes about half a day of migration
> cycles to reproduce this, on my Intel's laptop even with this patch I can hang the nested
> guest after 10-20 cycles. The symptoms look very similar to the issue that this patch
> tried to fix.
>
> Maybe we should keep the *comment* I added to document this funny TSC read behavior.
> When I implement the whole thing, maybe I add a comment only version of this patch
> for that.
Sure, that's a good idea.
Paolo
next prev parent reply other threads:[~2020-09-22 16:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 10:38 [PATCH v2 0/1] KVM: correctly restore the TSC value on nested migration Maxim Levitsky
2020-09-21 10:38 ` [PATCH v2 1/1] KVM: x86: fix MSR_IA32_TSC read for " Maxim Levitsky
[not found] ` <20200921162326.GB23989@linux.intel.com>
2020-09-22 12:50 ` Paolo Bonzini
2020-09-22 14:50 ` Maxim Levitsky
2020-09-22 15:39 ` Maxim Levitsky
2020-09-22 16:39 ` Paolo Bonzini [this message]
2020-09-24 17:33 ` Paolo Bonzini
2020-09-30 14:37 ` Maxim Levitsky
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