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x86/kvm: Disable all PV features on crash 

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/kvm_para.h
View File

@ -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 */

44
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);
@ -429,13 +430,14 @@ 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();
apf_task_wake_all();
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();
/*