[SRU][G][PATCH 4/5] x86/kvm: Disable all PV features on crash
Andrea Righi
andrea.righi at canonical.com
Thu May 20 13:39:47 UTC 2021
From: Vitaly Kuznetsov <vkuznets at redhat.com>
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 at redhat.com>
Message-Id: <20210414123544.1060604-5-vkuznets at redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
(backported from commit 3d6b84132d2a57b5a74100f6923a8feb679ac2ce)
Signed-off-by: Andrea Righi <andrea.righi at canonical.com>
---
arch/x86/include/asm/kvm_para.h | 6 -----
arch/x86/kernel/kvm.c | 46 +++++++++++++++++++++++----------
arch/x86/kernel/kvmclock.c | 21 ---------------
3 files changed, 33 insertions(+), 40 deletions(-)
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 43cc4a396bee..b2bfcbffcd74 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -91,7 +91,6 @@ unsigned int kvm_arch_para_hints(void);
void kvm_async_pf_task_wait_schedule(u32 token);
void kvm_async_pf_task_wake(u32 token);
u32 kvm_read_and_reset_apf_flags(void);
-void kvm_disable_steal_time(void);
bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token);
DECLARE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
@@ -136,11 +135,6 @@ static inline u32 kvm_read_and_reset_apf_flags(void)
return 0;
}
-static inline void kvm_disable_steal_time(void)
-{
- return;
-}
-
static __always_inline bool kvm_handle_async_pf(struct pt_regs *regs, u32 token)
{
return false;
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 74d6c0e344ba..adedf0fcb12b 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -34,6 +34,7 @@
#include <asm/hypervisor.h>
#include <asm/tlb.h>
#include <asm/cpuidle_haltpoll.h>
+#include <asm/reboot.h>
DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
@@ -354,6 +355,14 @@ static void kvm_pv_disable_apf(void)
pr_info("disable async PF for cpu %d\n", 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)
{
/*
@@ -396,14 +405,6 @@ 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);
@@ -431,13 +432,14 @@ 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();
}
@@ -597,7 +599,7 @@ 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;
}
@@ -606,7 +608,7 @@ 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;
}
@@ -647,6 +649,20 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
native_flush_tlb_others(flushmask, info);
}
+/*
+ * 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_guest_init(void)
{
int i;
@@ -665,7 +681,7 @@ static void __init kvm_guest_init(void)
pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
pv_ops.mmu.tlb_remove_table = tlb_remove_table;
pr_info("KVM setup pv remote TLB flush\n");
- }
+}
if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
apic_set_eoi_write(kvm_guest_apic_eoi_write);
@@ -688,6 +704,10 @@ 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);
/*
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index 327a0de01066..c4ac26333bc4 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -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;
@@ -204,23 +203,6 @@ 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);
@@ -350,9 +332,6 @@ 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();
/*
--
2.31.1
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