linux-kernel - Re: [PATCHv4 05/14] x86/kvm: Do not try to disable kvmclock if it was not enabled

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Message-ID: <20240104150526.52vbu4gownp7jm3i@box.shutemov.name>
Date: Thu, 4 Jan 2024 18:05:26 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>,
	Elena Reshetova <elena.reshetova@...el.com>,
	Jun Nakajima <jun.nakajima@...el.com>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>,
	Tom Lendacky <thomas.lendacky@....com>,
	Ashish Kalra <ashish.kalra@....com>,
	Kai Huang <kai.huang@...el.com>, Baoquan He <bhe@...hat.com>,
	kexec@...ts.infradead.org, linux-coco@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Vitaly Kuznetsov <vkuznets@...hat.com>,
	Wanpeng Li <wanpengli@...cent.com>
Subject: Re: [PATCHv4 05/14] x86/kvm: Do not try to disable kvmclock if it
 was not enabled

On Wed, Dec 13, 2023 at 09:22:34AM -0800, Sean Christopherson wrote:
> On Tue, Dec 12, 2023, Kirill A. Shutemov wrote:
> > On Tue, Dec 05, 2023 at 03:45:01AM +0300, Kirill A. Shutemov wrote:
> > > kvm_guest_cpu_offline() tries to disable kvmclock regardless if it is
> > > present in the VM. It leads to write to a MSR that doesn't exist on some
> > > configurations, namely in TDX guest:
> > > 
> > > 	unchecked MSR access error: WRMSR to 0x12 (tried to write 0x0000000000000000)
> > > 	at rIP: 0xffffffff8110687c (kvmclock_disable+0x1c/0x30)
> > > 
> > > kvmclock enabling is gated by CLOCKSOURCE and CLOCKSOURCE2 KVM paravirt
> > > features.
> > > 
> > > Do not disable kvmclock if it was not enabled.
> > > 
> > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> > > Fixes: c02027b5742b ("x86/kvm: Disable kvmclock on all CPUs on shutdown")
> > > Reviewed-by: Sean Christopherson <seanjc@...gle.com>
> > > Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> > > Cc: Paolo Bonzini <pbonzini@...hat.com>
> > > Cc: Wanpeng Li <wanpengli@...cent.com>
> > 
> > Paolo, Sean, any chance you can get it in through KVM tree while the rest
> > of kexec patchset is pending? The problem is visible on normal reboot too.
> 
> Paolo is going to grab this (possibly for 6.7-rc?).  I'll keep this tagged on my
> end in case that doesn't happen "soon".

Sean, any update on this?

-- 
  Kiryl Shutsemau / Kirill A. Shutemov