| Message ID | 20210520125625.12566-1-krzysztof.kozlowski@canonical.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v5.4+,1/3] x86/kvm: Teardown PV features on boot CPU as well | expand |
On 20/05/2021 12:47, Paolo Bonzini wrote: > On 20/05/21 14:56, Krzysztof Kozlowski wrote: >> From: Vitaly Kuznetsov <vkuznets@redhat.com> >> >> commit 8b79feffeca28c5459458fe78676b081e87c93a4 upstream. >> >> Various PV features (Async PF, PV EOI, steal time) work through memory >> shared with hypervisor and when we restore from hibernation we must >> properly teardown all these features to make sure hypervisor doesn't >> write to stale locations after we jump to the previously hibernated kernel >> (which can try to place anything there). For secondary CPUs the job is >> already done by kvm_cpu_down_prepare(), register syscore ops to do >> the same for boot CPU. >> >> Krzysztof: >> This fixes memory corruption visible after second resume from >> hibernation: > > Hi, you should include a cover letter detailing the differences between > the original patches and the backport. > > (I'll review it anyway, but it would have helped). My bad, I actually was not aware that backport differs that much. I can describe in v2. The patch context looks quite a different and now I see kvm_guest_cpu_offline() ends up within CONFIG_SMP for unclear reasons. Let me try to fix it in v2. Best regards, Krzysztof
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index e820568ed4d5..6b906a651fb1 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -24,6 +24,7 @@ #include <linux/debugfs.h> #include <linux/nmi.h> #include <linux/swait.h> +#include <linux/syscore_ops.h> #include <asm/timer.h> #include <asm/cpu.h> #include <asm/traps.h> @@ -558,17 +559,21 @@ static void kvm_guest_cpu_offline(void) static int kvm_cpu_online(unsigned int cpu) { - local_irq_disable(); + unsigned long flags; + + local_irq_save(flags); kvm_guest_cpu_init(); - local_irq_enable(); + local_irq_restore(flags); return 0; } static int kvm_cpu_down_prepare(unsigned int cpu) { - local_irq_disable(); + unsigned long flags; + + local_irq_save(flags); kvm_guest_cpu_offline(); - local_irq_enable(); + local_irq_restore(flags); return 0; } #endif @@ -606,6 +611,23 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask, native_flush_tlb_others(flushmask, info); } +static int kvm_suspend(void) +{ + kvm_guest_cpu_offline(); + + return 0; +} + +static void kvm_resume(void) +{ + kvm_cpu_online(raw_smp_processor_id()); +} + +static struct syscore_ops kvm_syscore_ops = { + .suspend = kvm_suspend, + .resume = kvm_resume, +}; + static void __init kvm_guest_init(void) { int i; @@ -649,6 +671,8 @@ static void __init kvm_guest_init(void) kvm_guest_cpu_init(); #endif + register_syscore_ops(&kvm_syscore_ops); + /* * Hard lockup detection is enabled by default. Disable it, as guests * can get false positives too easily, for example if the host is