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

[Sean Christopherson]

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 at linux.intel.com>
> > Fixes: c02027b5742b ("x86/kvm: Disable kvmclock on all CPUs on shutdown")
> > Reviewed-by: Sean Christopherson <seanjc at google.com>
> > Reviewed-by: Vitaly Kuznetsov <vkuznets at redhat.com>
> > Cc: Paolo Bonzini <pbonzini at redhat.com>
> > Cc: Wanpeng Li <wanpengli at tencent.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".