6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kirill A. Shutemov kirill.shutemov@linux.intel.com
commit 1c6d984f523f67ecfad1083bb04c55d91977bb15 upstream.
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@linux.intel.com Fixes: c02027b5742b ("x86/kvm: Disable kvmclock on all CPUs on shutdown") Reviewed-by: Sean Christopherson seanjc@google.com Reviewed-by: Vitaly Kuznetsov vkuznets@redhat.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Wanpeng Li wanpengli@tencent.com Cc: stable@vger.kernel.org Message-Id: 20231205004510.27164-6-kirill.shutemov@linux.intel.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/kvmclock.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
--- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -24,8 +24,8 @@
static int kvmclock __initdata = 1; static int kvmclock_vsyscall __initdata = 1; -static int msr_kvm_system_time __ro_after_init = MSR_KVM_SYSTEM_TIME; -static int msr_kvm_wall_clock __ro_after_init = MSR_KVM_WALL_CLOCK; +static int msr_kvm_system_time __ro_after_init; +static int msr_kvm_wall_clock __ro_after_init; static u64 kvm_sched_clock_offset __ro_after_init;
static int __init parse_no_kvmclock(char *arg) @@ -195,7 +195,8 @@ static void kvm_setup_secondary_clock(vo
void kvmclock_disable(void) { - native_write_msr(msr_kvm_system_time, 0, 0); + if (msr_kvm_system_time) + native_write_msr(msr_kvm_system_time, 0, 0); }
static void __init kvmclock_init_mem(void) @@ -294,7 +295,10 @@ void __init kvmclock_init(void) if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) { msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW; msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW; - } else if (!kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) { + } else if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) { + msr_kvm_system_time = MSR_KVM_SYSTEM_TIME; + msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK; + } else { return; }