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KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery

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KVM now supports using interrupt for 'page ready' APF event delivery and
legacy mechanism was deprecated. Switch KVM guests to the new one.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200525144125.143875-9-vkuznets@redhat.com>
[Use HYPERVISOR_CALLBACK_VECTOR instead of a separate vector. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2020-05-25 16:41:23 +02:00 committed by Paolo Bonzini
parent 49b3deaad3
commit b1d405751c
5 changed files with 52 additions and 16 deletions
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1
arch/x86/Kconfig
View File

@ -801,6 +801,7 @@ config KVM_GUEST
depends on PARAVIRT
select PARAVIRT_CLOCK
select ARCH_CPUIDLE_HALTPOLL
select X86_HV_CALLBACK_VECTOR
default y
---help---
This option enables various optimizations for running under the KVM

5
arch/x86/entry/entry_32.S
View File

@ -1475,6 +1475,11 @@ BUILD_INTERRUPT3(hv_stimer0_callback_vector, HYPERV_STIMER0_VECTOR,
#endif /* CONFIG_HYPERV */
#ifdef CONFIG_KVM_GUEST
BUILD_INTERRUPT3(kvm_async_pf_vector, HYPERVISOR_CALLBACK_VECTOR,
kvm_async_pf_intr)
#endif
SYM_CODE_START(page_fault)
ASM_CLAC
pushl $do_page_fault

5
arch/x86/entry/entry_64.S
View File

@ -1190,6 +1190,11 @@ apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \
acrn_hv_callback_vector acrn_hv_vector_handler
#endif
#ifdef CONFIG_KVM_GUEST
apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \
kvm_async_pf_vector kvm_async_pf_intr
#endif
idtentry debug do_debug has_error_code=0 paranoid=1 shift_ist=IST_INDEX_DB ist_offset=DB_STACK_OFFSET
idtentry int3 do_int3 has_error_code=0 create_gap=1
idtentry stack_segment do_stack_segment has_error_code=1

7
arch/x86/include/asm/kvm_para.h
View File

@ -4,6 +4,7 @@
#include <asm/processor.h>
#include <asm/alternative.h>
#include <linux/interrupt.h>
#include <uapi/asm/kvm_para.h>
extern void kvmclock_init(void);
@ -104,6 +105,12 @@ static __always_inline bool kvm_handle_async_pf(struct pt_regs *regs, u32 token)
return false;
}
extern __visible void kvm_async_pf_vector(void);
#ifdef CONFIG_TRACING
#define trace_kvm_async_pf_vector kvm_async_pf_vector
#endif
__visible void __irq_entry kvm_async_pf_intr(struct pt_regs *regs);
#ifdef CONFIG_PARAVIRT_SPINLOCKS
void __init kvm_spinlock_init(void);
#else /* !CONFIG_PARAVIRT_SPINLOCKS */

50
arch/x86/kernel/kvm.c
View File

@ -233,15 +233,10 @@ NOKPROBE_SYMBOL(kvm_read_and_reset_apf_flags);
bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
{
u32 reason = kvm_read_and_reset_apf_flags();
u32 flags = kvm_read_and_reset_apf_flags();
switch (reason) {
case KVM_PV_REASON_PAGE_NOT_PRESENT:
case KVM_PV_REASON_PAGE_READY:
break;
default:
if (!flags)
return false;
}
/*
* If the host managed to inject an async #PF into an interrupt
@ -251,20 +246,39 @@ bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
panic("Host injected async #PF in interrupt disabled region\n");
if (reason == KVM_PV_REASON_PAGE_NOT_PRESENT) {
if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
if (unlikely(!(user_mode(regs))))
panic("Host injected async #PF in kernel mode\n");
/* Page is swapped out by the host. */
kvm_async_pf_task_wait_schedule(token);
} else {
rcu_irq_enter();
kvm_async_pf_task_wake(token);
rcu_irq_exit();
return true;
}
WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
return true;
}
NOKPROBE_SYMBOL(__kvm_handle_async_pf);
__visible void __irq_entry kvm_async_pf_intr(struct pt_regs *regs)
{
u32 token;
entering_ack_irq();
inc_irq_stat(irq_hv_callback_count);
if (__this_cpu_read(apf_reason.enabled)) {
token = __this_cpu_read(apf_reason.token);
rcu_irq_enter();
kvm_async_pf_task_wake(token);
rcu_irq_exit();
__this_cpu_write(apf_reason.token, 0);
wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
}
exiting_irq();
}
static void __init paravirt_ops_setup(void)
{
pv_info.name = "KVM";
@ -308,17 +322,19 @@ static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
static void kvm_guest_cpu_init(void)
{
if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
u64 pa;
if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
pa |= KVM_ASYNC_PF_ENABLED;
pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
__this_cpu_write(apf_reason.enabled, 1);
pr_info("KVM setup async PF for cpu %d\n", smp_processor_id());
@ -643,8 +659,10 @@ static void __init kvm_guest_init(void)
if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
apic_set_eoi_write(kvm_guest_apic_eoi_write);
if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf)
if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
static_branch_enable(&kvm_async_pf_enabled);
alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, kvm_async_pf_vector);
}
#ifdef CONFIG_SMP
smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;