| Message ID | 20210520125625.12566-1-krzysztof.kozlowski@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [stable,v5.4+,1/3] x86/kvm: Teardown PV features on boot CPU as well | expand |
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). Paolo > BUG: Bad page state in process dbus-daemon pfn:18b01 > page:ffffea000062c040 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 compound_mapcount: -30591 > flags: 0xfffffc0078141(locked|error|workingset|writeback|head|mappedtodisk|reclaim) > raw: 000fffffc0078141 dead0000000002d0 dead000000000100 0000000000000000 > raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000 > page dumped because: PAGE_FLAGS_CHECK_AT_PREP flag set > bad because of flags: 0x78141(locked|error|workingset|writeback|head|mappedtodisk|reclaim) > > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > Message-Id: <20210414123544.1060604-3-vkuznets@redhat.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > Signed-off-by: Andrea Righi <andrea.righi@canonical.com> > [krzysztof: Extend the commit message] > Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> > --- > > Backport to v5.4 seems reasonable. Might have sense to earlier versions, > but this was not tested/investigated. > > arch/x86/kernel/kvm.c | 32 ++++++++++++++++++++++++++++---- > 1 file changed, 28 insertions(+), 4 deletions(-) > > 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 >
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