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x86/kvm: Disable all PV features on crash

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commit 3d6b84132d2a57b5a74100f6923a8feb679ac2ce upstream.

Crash shutdown handler only disables kvmclock and steal time, other PV
features remain active so we risk corrupting memory or getting some
side-effects in kdump kernel. Move crash handler to kvm.c and unify
with CPU offline.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210414123544.1060604-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vitaly Kuznetsov 2021-05-31 16:03:47 +02:00 committed by Greg Kroah-Hartman
parent 9084fe1b35
commit 97e814e6b5
3 changed files with 32 additions and 39 deletions
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6
arch/x86/include/asm/kvm_para.h
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@ -91,7 +91,6 @@ unsigned int kvm_arch_para_hints(void);
void kvm_async_pf_task_wait(u32 token, int interrupt_kernel);
void kvm_async_pf_task_wake(u32 token);
u32 kvm_read_and_reset_pf_reason(void);
extern void kvm_disable_steal_time(void);
void do_async_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address);
#ifdef CONFIG_PARAVIRT_SPINLOCKS
@ -125,11 +124,6 @@ static inline u32 kvm_read_and_reset_pf_reason(void)
{
return 0;
}
static inline void kvm_disable_steal_time(void)
{
return;
}
#endif
#endif /* _ASM_X86_KVM_PARA_H */

42
arch/x86/kernel/kvm.c
View File

@ -34,6 +34,7 @@
#include <asm/apicdef.h>
#include <asm/hypervisor.h>
#include <asm/tlb.h>
#include <asm/reboot.h>
static int kvmapf = 1;
@ -352,6 +353,14 @@ static void kvm_pv_disable_apf(void)
smp_processor_id());
}
static void kvm_disable_steal_time(void)
{
if (!has_steal_clock)
return;
wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
}
static void kvm_pv_guest_cpu_reboot(void *unused)
{
/*
@ -394,14 +403,6 @@ static u64 kvm_steal_clock(int cpu)
return steal;
}
void kvm_disable_steal_time(void)
{
if (!has_steal_clock)
return;
wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
}
static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
{
early_set_memory_decrypted((unsigned long) ptr, size);
@ -429,12 +430,13 @@ static void __init sev_map_percpu_data(void)
}
}
static void kvm_guest_cpu_offline(void)
static void kvm_guest_cpu_offline(bool shutdown)
{
kvm_disable_steal_time();
if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
wrmsrl(MSR_KVM_PV_EOI_EN, 0);
kvm_pv_disable_apf();
if (!shutdown)
apf_task_wake_all();
kvmclock_disable();
}
@ -573,7 +575,7 @@ static int kvm_cpu_down_prepare(unsigned int cpu)
unsigned long flags;
local_irq_save(flags);
kvm_guest_cpu_offline();
kvm_guest_cpu_offline(false);
local_irq_restore(flags);
return 0;
}
@ -582,7 +584,7 @@ static int kvm_cpu_down_prepare(unsigned int cpu)
static int kvm_suspend(void)
{
kvm_guest_cpu_offline();
kvm_guest_cpu_offline(false);
return 0;
}
@ -597,6 +599,20 @@ static struct syscore_ops kvm_syscore_ops = {
.resume = kvm_resume,
};
/*
* After a PV feature is registered, the host will keep writing to the
* registered memory location. If the guest happens to shutdown, this memory
* won't be valid. In cases like kexec, in which you install a new kernel, this
* means a random memory location will be kept being written.
*/
#ifdef CONFIG_KEXEC_CORE
static void kvm_crash_shutdown(struct pt_regs *regs)
{
kvm_guest_cpu_offline(true);
native_machine_crash_shutdown(regs);
}
#endif
static void __init kvm_apf_trap_init(void)
{
update_intr_gate(X86_TRAP_PF, async_page_fault);
@ -673,6 +689,10 @@ static void __init kvm_guest_init(void)
kvm_guest_cpu_init();
#endif
#ifdef CONFIG_KEXEC_CORE
machine_ops.crash_shutdown = kvm_crash_shutdown;
#endif
register_syscore_ops(&kvm_syscore_ops);
/*

21
arch/x86/kernel/kvmclock.c
View File

@ -20,7 +20,6 @@
#include <asm/hypervisor.h>
#include <asm/mem_encrypt.h>
#include <asm/x86_init.h>
#include <asm/reboot.h>
#include <asm/kvmclock.h>
static int kvmclock __initdata = 1;
@ -197,23 +196,6 @@ static void kvm_setup_secondary_clock(void)
}
#endif
/*
* After the clock is registered, the host will keep writing to the
* registered memory location. If the guest happens to shutdown, this memory
* won't be valid. In cases like kexec, in which you install a new kernel, this
* means a random memory location will be kept being written. So before any
* kind of shutdown from our side, we unregister the clock by writing anything
* that does not have the 'enable' bit set in the msr
*/
#ifdef CONFIG_KEXEC_CORE
static void kvm_crash_shutdown(struct pt_regs *regs)
{
native_write_msr(msr_kvm_system_time, 0, 0);
kvm_disable_steal_time();
native_machine_crash_shutdown(regs);
}
#endif
void kvmclock_disable(void)
{
native_write_msr(msr_kvm_system_time, 0, 0);
@ -344,9 +326,6 @@ void __init kvmclock_init(void)
#endif
x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
#ifdef CONFIG_KEXEC_CORE
machine_ops.crash_shutdown = kvm_crash_shutdown;
#endif
kvm_get_preset_lpj();
/*