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Date: Mon, 25 May 2020 16:41:23 +0200
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: kvm@...r.kernel.org, x86@...nel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
"H. Peter Anvin" <hpa@...or.com>,
Wanpeng Li <wanpengli@...cent.com>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Jim Mattson <jmattson@...gle.com>,
Vivek Goyal <vgoyal@...hat.com>, Gavin Shan <gshan@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 08/10] KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery
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@...hat.com>
---
arch/x86/entry/entry_32.S | 5 ++++
arch/x86/entry/entry_64.S | 5 ++++
arch/x86/include/asm/hardirq.h | 3 ++
arch/x86/include/asm/irq_vectors.h | 6 +++-
arch/x86/include/asm/kvm_para.h | 6 ++++
arch/x86/kernel/irq.c | 9 ++++++
arch/x86/kernel/kvm.c | 45 ++++++++++++++++++++++--------
7 files changed, 66 insertions(+), 13 deletions(-)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index b67bae7091d7..d574dadcb2a1 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -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, KVM_ASYNC_PF_VECTOR,
+ kvm_async_pf_intr)
+#endif
+
SYM_CODE_START(page_fault)
ASM_CLAC
pushl $do_page_fault
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 3063aa9090f9..138f5c5aca2e 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1190,6 +1190,11 @@ apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \
acrn_hv_callback_vector acrn_hv_vector_handler
#endif
+#ifdef CONFIG_KVM_GUEST
+apicinterrupt3 KVM_ASYNC_PF_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
diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h
index 07533795b8d2..be0fbb15ad7f 100644
--- a/arch/x86/include/asm/hardirq.h
+++ b/arch/x86/include/asm/hardirq.h
@@ -44,6 +44,9 @@ typedef struct {
unsigned int irq_hv_reenlightenment_count;
unsigned int hyperv_stimer0_count;
#endif
+#ifdef CONFIG_KVM_GUEST
+ unsigned int kvm_async_pf_pageready_count;
+#endif
} ____cacheline_aligned irq_cpustat_t;
DECLARE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 889f8b1b5b7f..8879a9ecd908 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -104,7 +104,11 @@
#define HYPERV_STIMER0_VECTOR 0xed
#endif
-#define LOCAL_TIMER_VECTOR 0xec
+#ifdef CONFIG_KVM_GUEST
+#define KVM_ASYNC_PF_VECTOR 0xec
+#endif
+
+#define LOCAL_TIMER_VECTOR 0xeb
#define NR_VECTORS 256
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 2a3102fee189..a075cd8fa5c7 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -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);
@@ -93,6 +94,11 @@ void kvm_async_pf_task_wake(u32 token);
u32 kvm_read_and_reset_apf_flags(void);
extern void kvm_disable_steal_time(void);
void do_async_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address);
+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);
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index c7965ff429c5..a4c2f25ad74d 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -159,6 +159,15 @@ int arch_show_interrupts(struct seq_file *p, int prec)
irq_stats(j)->hyperv_stimer0_count);
seq_puts(p, " Hyper-V stimer0 interrupts\n");
}
+#endif
+#ifdef CONFIG_KVM_GUEST
+ if (test_bit(KVM_ASYNC_PF_VECTOR, system_vectors)) {
+ seq_printf(p, "%*s: ", prec, "APF");
+ for_each_online_cpu(j)
+ seq_printf(p, "%10u ",
+ irq_stats(j)->kvm_async_pf_pageready_count);
+ seq_puts(p, " KVM async PF page ready interrupts\n");
+ }
#endif
seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
#if defined(CONFIG_X86_IO_APIC)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 340df5dab30d..79730eaef1e1 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -245,23 +245,39 @@ NOKPROBE_SYMBOL(kvm_read_and_reset_apf_flags);
dotraplinkage void
do_async_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address)
{
- switch (kvm_read_and_reset_apf_flags()) {
- default:
+ u32 flags = kvm_read_and_reset_apf_flags();
+
+ if (!flags) {
+ /* This is a normal page fault */
do_page_fault(regs, error_code, address);
- break;
- case KVM_PV_REASON_PAGE_NOT_PRESENT:
+ return;
+ } else if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
/* page is swapped out by the host. */
kvm_async_pf_task_wait((u32)address, !user_mode(regs));
- break;
- case KVM_PV_REASON_PAGE_READY:
- rcu_irq_enter();
- kvm_async_pf_task_wake((u32)address);
- rcu_irq_exit();
- break;
+ } else {
+ WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
}
}
NOKPROBE_SYMBOL(do_async_page_fault);
+__visible void __irq_entry kvm_async_pf_intr(struct pt_regs *regs)
+{
+ u32 token;
+
+ entering_ack_irq();
+
+ inc_irq_stat(kvm_async_pf_pageready_count);
+
+ if (__this_cpu_read(apf_reason.enabled)) {
+ token = __this_cpu_read(apf_reason.token);
+ kvm_async_pf_task_wake(token);
+ __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";
@@ -305,17 +321,19 @@ 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) {
+ if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
#ifdef CONFIG_PREEMPTION
pa |= KVM_ASYNC_PF_SEND_ALWAYS;
#endif
- 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, KVM_ASYNC_PF_VECTOR);
+
wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
__this_cpu_write(apf_reason.enabled, 1);
printk(KERN_INFO"KVM setup async PF for cpu %d\n",
@@ -649,6 +667,9 @@ 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_INT))
+ alloc_intr_gate(KVM_ASYNC_PF_VECTOR, kvm_async_pf_vector);
+
#ifdef CONFIG_SMP
smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
--
2.25.4
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