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x86/kvm: Teardown PV features on boot CPU as well

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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.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210414123544.1060604-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2021-04-14 14:35:41 +02:00 committed by Paolo Bonzini
parent 0a269a008f
commit 8b79feffec
1 changed files with 43 additions and 19 deletions
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62
arch/x86/kernel/kvm.c
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@ -26,6 +26,7 @@
#include <linux/kprobes.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>
@ -451,6 +452,25 @@ 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
static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
@ -635,33 +655,35 @@ static void __init kvm_smp_prepare_boot_cpu(void)
kvm_spinlock_init();
}
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)
{
local_irq_disable();
kvm_guest_cpu_init();
local_irq_enable();
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
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;
@ -704,6 +726,8 @@ 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