On 31/05/21 16:03, 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:
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
arch/x86/kernel/kvm.c | 57 +++++++++++++++++++++++++++++++------------ 1 file changed, 41 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index e820568ed4d5..82a2756e0ef8 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> @@ -428,6 +429,25 @@ static void __init sev_map_percpu_data(void) } } +static void kvm_guest_cpu_offline(void) +{
- kvm_disable_steal_time();
- if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
wrmsrl(MSR_KVM_PV_EOI_EN, 0);- kvm_pv_disable_apf();
- apf_task_wake_all();
+}
+static int kvm_cpu_online(unsigned int cpu) +{
- unsigned long flags;
- local_irq_save(flags);
- kvm_guest_cpu_init();
- local_irq_restore(flags);
- return 0;
+}
- #ifdef CONFIG_SMP #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG)
@@ -547,31 +567,34 @@ static void __init kvm_smp_prepare_boot_cpu(void) kvm_spinlock_init(); } -static void kvm_guest_cpu_offline(void) +static int kvm_cpu_down_prepare(unsigned int cpu) {
- kvm_disable_steal_time();
- if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
wrmsrl(MSR_KVM_PV_EOI_EN, 0);- kvm_pv_disable_apf();
- apf_task_wake_all();
-}
- unsigned long flags;
-static int kvm_cpu_online(unsigned int cpu) -{
- local_irq_disable();
- kvm_guest_cpu_init();
- local_irq_enable();
- local_irq_save(flags);
- kvm_guest_cpu_offline();
- local_irq_restore(flags); return 0; }
-static int kvm_cpu_down_prepare(unsigned int cpu) +#endif
+static int kvm_suspend(void) {
- local_irq_disable(); kvm_guest_cpu_offline();
- local_irq_enable();
- return 0; }
-#endif
+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_apf_trap_init(void) { @@ -649,6 +672,8 @@ 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
Acked-by: Paolo Bonzini pbonzini@redhat.com