[PATCH v4 08/12] Inject asynchronous page fault into a guest if page is swapped out.

From: Gleb Natapov
Date: Tue Jul 06 2010 - 12:26:19 EST

If guest access swapped out memory do not swap it in from vcpu thread
context. Setup slow work to do swapping and send async page fault to
a guest.

Allow async page fault injection only when guest is in user mode since
otherwise guest may be in non-sleepable context and will not be able to
reschedule.

Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 16 +++
arch/x86/kvm/Kconfig | 2 +
arch/x86/kvm/mmu.c | 35 +++++-
arch/x86/kvm/paging_tmpl.h | 17 +++-
arch/x86/kvm/x86.c | 63 +++++++++-
include/linux/kvm_host.h | 31 +++++
include/trace/events/kvm.h | 60 +++++++++
virt/kvm/Kconfig | 3 +
virt/kvm/kvm_main.c | 263 ++++++++++++++++++++++++++++++++++++++-
9 files changed, 481 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 245831a..db514ea 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -366,7 +366,9 @@ struct kvm_vcpu_arch {
cpumask_var_t wbinvd_dirty_mask;

u32 __user *apf_data;
+ u32 apf_memslot_ver;
u64 apf_msr_val;
+ u32 async_pf_id;
};

struct kvm_arch {
@@ -444,6 +446,8 @@ struct kvm_vcpu_stat {
u32 hypercalls;
u32 irq_injections;
u32 nmi_injections;
+ u32 apf_not_present;
+ u32 apf_present;
};

struct kvm_x86_ops {
@@ -528,6 +532,10 @@ struct kvm_x86_ops {
const struct trace_print_flags *exit_reasons_str;
};

+struct kvm_arch_async_pf {
+ u32 token;
+};
+
extern struct kvm_x86_ops *kvm_x86_ops;

int kvm_mmu_module_init(void);
@@ -763,4 +771,12 @@ void kvm_set_shared_msr(unsigned index, u64 val, u64 mask);

bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip);

+struct kvm_async_pf;
+
+void kvm_arch_inject_async_page_not_present(struct kvm_vcpu *vcpu,
+ struct kvm_async_pf *work);
+void kvm_arch_inject_async_page_present(struct kvm_vcpu *vcpu,
+ struct kvm_async_pf *work);
+bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu);
#endif /* _ASM_X86_KVM_HOST_H */
+
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 970bbd4..2461284 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -28,6 +28,8 @@ config KVM
select HAVE_KVM_IRQCHIP
select HAVE_KVM_EVENTFD
select KVM_APIC_ARCHITECTURE
+ select KVM_ASYNC_PF
+ select SLOW_WORK
select USER_RETURN_NOTIFIER
select KVM_MMIO
---help---
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index c515753..a49565b 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -21,6 +21,7 @@
#include "mmu.h"
#include "x86.h"
#include "kvm_cache_regs.h"
+#include "x86.h"

#include <linux/kvm_host.h>
#include <linux/types.h>
@@ -2264,6 +2265,21 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
error_code & PFERR_WRITE_MASK, gfn);
}

+int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn)
+{
+ struct kvm_arch_async_pf arch;
+ arch.token = (vcpu->arch.async_pf_id++ << 12) | vcpu->vcpu_id;
+ return kvm_setup_async_pf(vcpu, gva, gfn, &arch);
+}
+
+static bool can_do_async_pf(struct kvm_vcpu *vcpu)
+{
+ if (!vcpu->arch.apf_data || kvm_event_needs_reinjection(vcpu))
+ return false;
+
+ return !!kvm_x86_ops->get_cpl(vcpu);
+}
+
static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
u32 error_code)
{
@@ -2272,6 +2288,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
int level;
gfn_t gfn = gpa >> PAGE_SHIFT;
unsigned long mmu_seq;
+ bool async;

ASSERT(vcpu);
ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
@@ -2286,7 +2303,23 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,

mmu_seq = vcpu->kvm->mmu_notifier_seq;
smp_rmb();
- pfn = gfn_to_pfn(vcpu->kvm, gfn);
+
+ if (can_do_async_pf(vcpu)) {
+ pfn = gfn_to_pfn_async(vcpu->kvm, gfn, &async);
+ trace_kvm_try_async_get_page(async, pfn);
+ } else {
+do_sync:
+ async = false;
+ pfn = gfn_to_pfn(vcpu->kvm, gfn);
+ }
+
+ if (async) {
+ if (!kvm_arch_setup_async_pf(vcpu, gpa, gfn))
+ goto do_sync;
+ return 0;
+ }
+
+ /* mmio */
if (is_error_pfn(pfn))
return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
spin_lock(&vcpu->kvm->mmu_lock);
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 3350c02..26d6b74 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -423,6 +423,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
pfn_t pfn;
int level = PT_PAGE_TABLE_LEVEL;
unsigned long mmu_seq;
+ bool async;

pgprintk("%s: addr %lx err %x\n", __func__, addr, error_code);
kvm_mmu_audit(vcpu, "pre page fault");
@@ -454,7 +455,21 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,

mmu_seq = vcpu->kvm->mmu_notifier_seq;
smp_rmb();
- pfn = gfn_to_pfn(vcpu->kvm, walker.gfn);
+
+ if (can_do_async_pf(vcpu)) {
+ pfn = gfn_to_pfn_async(vcpu->kvm, walker.gfn, &async);
+ trace_kvm_try_async_get_page(async, pfn);
+ } else {
+do_sync:
+ async = false;
+ pfn = gfn_to_pfn(vcpu->kvm, walker.gfn);
+ }
+
+ if (async) {
+ if (!kvm_arch_setup_async_pf(vcpu, addr, walker.gfn))
+ goto do_sync;
+ return 0;
+ }

/* mmio */
if (is_error_pfn(pfn))
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 744f8c1..6b7542f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -118,6 +118,8 @@ static DEFINE_PER_CPU(struct kvm_shared_msrs, shared_msrs);
struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "pf_fixed", VCPU_STAT(pf_fixed) },
{ "pf_guest", VCPU_STAT(pf_guest) },
+ { "apf_not_present", VCPU_STAT(apf_not_present) },
+ { "apf_present", VCPU_STAT(apf_present) },
{ "tlb_flush", VCPU_STAT(tlb_flush) },
{ "invlpg", VCPU_STAT(invlpg) },
{ "exits", VCPU_STAT(exits) },
@@ -1226,6 +1228,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)

if (!(data & KVM_ASYNC_PF_ENABLED)) {
vcpu->arch.apf_data = NULL;
+ kvm_clear_async_pf_completion_queue(vcpu);
return 0;
}

@@ -1240,6 +1243,8 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
vcpu->arch.apf_data = NULL;
return 1;
}
+ vcpu->arch.apf_memslot_ver = vcpu->kvm->memslot_version;
+ kvm_async_pf_wakeup_all(vcpu);
return 0;
}

@@ -4721,6 +4726,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (unlikely(r))
goto out;

+ kvm_check_async_pf_completion(vcpu);
+
preempt_disable();

kvm_x86_ops->prepare_guest_switch(vcpu);
@@ -5393,6 +5400,8 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
vcpu->arch.apf_data = NULL;
vcpu->arch.apf_msr_val = 0;

+ kvm_clear_async_pf_completion_queue(vcpu);
+
return kvm_x86_ops->vcpu_reset(vcpu);
}

@@ -5534,8 +5543,10 @@ static void kvm_free_vcpus(struct kvm *kvm)
/*
* Unpin any mmu pages first.
*/
- kvm_for_each_vcpu(i, vcpu, kvm)
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ kvm_clear_async_pf_completion_queue(vcpu);
kvm_unload_vcpu_mmu(vcpu);
+ }
kvm_for_each_vcpu(i, vcpu, kvm)
kvm_arch_vcpu_free(vcpu);

@@ -5647,6 +5658,7 @@ void kvm_arch_flush_shadow(struct kvm *kvm)
int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
{
return vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE
+ || !list_empty_careful(&vcpu->async_pf_done)
|| vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED
|| vcpu->arch.nmi_pending ||
(kvm_arch_interrupt_allowed(vcpu) &&
@@ -5704,6 +5716,55 @@ void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
}
EXPORT_SYMBOL_GPL(kvm_set_rflags);

+static int apf_put_user(struct kvm_vcpu *vcpu, u32 val)
+{
+ if (unlikely(vcpu->arch.apf_memslot_ver !=
+ vcpu->kvm->memslot_version)) {
+ u64 gpa = vcpu->arch.apf_msr_val & ~0x3f;
+ unsigned long addr;
+ int offset = offset_in_page(gpa);
+
+ addr = gfn_to_hva(vcpu->kvm, gpa >> PAGE_SHIFT);
+ vcpu->arch.apf_data = (u32 __user*)(addr + offset);
+ if (kvm_is_error_hva(addr)) {
+ vcpu->arch.apf_data = NULL;
+ return -EFAULT;
+ }
+ }
+
+ return put_user(val, vcpu->arch.apf_data);
+}
+
+void kvm_arch_inject_async_page_not_present(struct kvm_vcpu *vcpu,
+ struct kvm_async_pf *work)
+{
+ if (!apf_put_user(vcpu, KVM_PV_REASON_PAGE_NOT_PRESENT)) {
+ kvm_inject_page_fault(vcpu, work->arch.token, 0);
+ ++vcpu->stat.apf_not_present;
+ trace_kvm_send_async_pf(work->arch.token, work->gva,
+ KVM_PV_REASON_PAGE_NOT_PRESENT);
+ }
+}
+
+void kvm_arch_inject_async_page_present(struct kvm_vcpu *vcpu,
+ struct kvm_async_pf *work)
+{
+ if (is_error_page(work->page))
+ work->arch.token = ~0; /* broadcast wakeup */
+ if (!apf_put_user(vcpu, KVM_PV_REASON_PAGE_READY)) {
+ kvm_inject_page_fault(vcpu, work->arch.token, 0);
+ ++vcpu->stat.apf_present;
+ trace_kvm_send_async_pf(work->arch.token, work->gva,
+ KVM_PV_REASON_PAGE_READY);
+ }
+}
+
+bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu)
+{
+ return !kvm_event_needs_reinjection(vcpu) &&
+ kvm_x86_ops->interrupt_allowed(vcpu);
+}
+
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_page_fault);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 64f62f1..09c646f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -16,6 +16,7 @@
#include <linux/mm.h>
#include <linux/preempt.h>
#include <linux/msi.h>
+#include <linux/slow-work.h>
#include <asm/signal.h>

#include <linux/kvm.h>
@@ -73,6 +74,27 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx,
int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
struct kvm_io_device *dev);

+#ifdef CONFIG_KVM_ASYNC_PF
+struct kvm_async_pf {
+ struct slow_work work;
+ struct list_head link;
+ struct list_head queue;
+ struct kvm_vcpu *vcpu;
+ struct mm_struct *mm;
+ gva_t gva;
+ unsigned long addr;
+ struct kvm_arch_async_pf arch;
+ struct page *page;
+ atomic_t used;
+};
+
+void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu);
+void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu);
+int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
+ struct kvm_arch_async_pf *arch);
+int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
+#endif
+
struct kvm_vcpu {
struct kvm *kvm;
#ifdef CONFIG_PREEMPT_NOTIFIERS
@@ -103,6 +125,14 @@ struct kvm_vcpu {
gpa_t mmio_phys_addr;
#endif

+#ifdef CONFIG_KVM_ASYNC_PF
+ u32 async_pf_queued;
+ struct list_head async_pf_queue;
+ struct list_head async_pf_done;
+ spinlock_t async_pf_lock;
+ struct kvm_async_pf *async_pf_work;
+#endif
+
struct kvm_vcpu_arch arch;
};

@@ -296,6 +326,7 @@ void kvm_release_page_dirty(struct page *page);
void kvm_set_page_dirty(struct page *page);
void kvm_set_page_accessed(struct page *page);

+pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async);
pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
struct kvm_memory_slot *slot, gfn_t gfn);
diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
index 6dd3a51..6d9f0c2 100644
--- a/include/trace/events/kvm.h
+++ b/include/trace/events/kvm.h
@@ -185,6 +185,66 @@ TRACE_EVENT(kvm_age_page,
__entry->referenced ? "YOUNG" : "OLD")
);

+#ifdef CONFIG_KVM_ASYNC_PF
+TRACE_EVENT(
+ kvm_try_async_get_page,
+ TP_PROTO(bool async, u64 pfn),
+ TP_ARGS(async, pfn),
+
+ TP_STRUCT__entry(
+ __field(__u64, pfn)
+ ),
+
+ TP_fast_assign(
+ __entry->pfn = (!async) ? pfn : (u64)-1;
+ ),
+
+ TP_printk("pfn %#llx", __entry->pfn)
+);
+
+TRACE_EVENT(
+ kvm_send_async_pf,
+ TP_PROTO(u64 token, u64 gva, u64 reason),
+ TP_ARGS(token, gva, reason),
+
+ TP_STRUCT__entry(
+ __field(__u64, token)
+ __field(__u64, gva)
+ __field(bool, np)
+ ),
+
+ TP_fast_assign(
+ __entry->token = token;
+ __entry->gva = gva;
+ __entry->np = (reason == KVM_PV_REASON_PAGE_NOT_PRESENT);
+ ),
+
+ TP_printk("token %#llx gva %#llx %s", __entry->token, __entry->gva,
+ __entry->np ? "not present" : "ready")
+);
+
+TRACE_EVENT(
+ kvm_async_pf_completed,
+ TP_PROTO(unsigned long address, struct page *page, u64 gva),
+ TP_ARGS(address, page, gva),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, address)
+ __field(struct page*, page)
+ __field(u64, gva)
+ ),
+
+ TP_fast_assign(
+ __entry->address = address;
+ __entry->page = page;
+ __entry->gva = gva;
+ ),
+
+ TP_printk("gva %#llx address %#lx pfn %lx", __entry->gva,
+ __entry->address, page_to_pfn(__entry->page))
+);
+#endif
+
#endif /* _TRACE_KVM_MAIN_H */

/* This part must be outside protection */
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 7f1178f..f63ccb0 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -15,3 +15,6 @@ config KVM_APIC_ARCHITECTURE

config KVM_MMIO
bool
+
+config KVM_ASYNC_PF
+ bool
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 733558c..0656054 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -78,6 +78,11 @@ static atomic_t hardware_enable_failed;
struct kmem_cache *kvm_vcpu_cache;
EXPORT_SYMBOL_GPL(kvm_vcpu_cache);

+#ifdef CONFIG_KVM_ASYNC_PF
+#define ASYNC_PF_PER_VCPU 100
+static struct kmem_cache *async_pf_cache;
+#endif
+
static __read_mostly struct preempt_ops kvm_preempt_ops;

struct dentry *kvm_debugfs_dir;
@@ -183,6 +188,11 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
vcpu->kvm = kvm;
vcpu->vcpu_id = id;
init_waitqueue_head(&vcpu->wq);
+#ifdef CONFIG_KVM_ASYNC_PF
+ INIT_LIST_HEAD(&vcpu->async_pf_done);
+ INIT_LIST_HEAD(&vcpu->async_pf_queue);
+ spin_lock_init(&vcpu->async_pf_lock);
+#endif

page = alloc_page(GFP_KERNEL | __GFP_ZERO);
if (!page) {
@@ -935,7 +945,7 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
}
EXPORT_SYMBOL_GPL(gfn_to_hva);

-static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
+static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool *async)
{
struct page *page[1];
int npages;
@@ -943,7 +953,19 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)

might_sleep();

- npages = get_user_pages_fast(addr, 1, 1, page);
+ if (async) {
+#ifdef CONFIG_X86
+ npages = __get_user_pages_fast(addr, 1, 1, page);
+#endif
+ if (unlikely(npages != 1)) {
+ down_read(&current->mm->mmap_sem);
+ npages = get_user_pages_noio(current, current->mm,
+ addr, 1, 1, 0, page,
+ NULL);
+ up_read(&current->mm->mmap_sem);
+ }
+ } else
+ npages = get_user_pages_fast(addr, 1, 1, page);

if (unlikely(npages != 1)) {
struct vm_area_struct *vma;
@@ -959,6 +981,9 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)

if (vma == NULL || addr < vma->vm_start ||
!(vma->vm_flags & VM_PFNMAP)) {
+ if (async && !(vma->vm_flags & VM_PFNMAP) &&
+ (vma->vm_flags & VM_WRITE))
+ *async = true;
up_read(&current->mm->mmap_sem);
get_page(bad_page);
return page_to_pfn(bad_page);
@@ -973,25 +998,37 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
return pfn;
}

-pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+static inline pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool *async)
{
unsigned long addr;

+ if (async)
+ *async = false;
addr = gfn_to_hva(kvm, gfn);
if (kvm_is_error_hva(addr)) {
get_page(bad_page);
return page_to_pfn(bad_page);
}

- return hva_to_pfn(kvm, addr);
+ return hva_to_pfn(kvm, addr, async);
+}
+
+pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+{
+ return __gfn_to_pfn(kvm, gfn, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn);

+pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async)
+{
+ return __gfn_to_pfn(kvm, gfn, async);
+}
+
pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
struct kvm_memory_slot *slot, gfn_t gfn)
{
unsigned long addr = gfn_to_hva_memslot(slot, gfn);
- return hva_to_pfn(kvm, addr);
+ return hva_to_pfn(kvm, addr, NULL);
}

struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
@@ -1204,6 +1241,196 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
}
}

+#ifdef CONFIG_KVM_ASYNC_PF
+static void async_pf_work_free(struct kvm_async_pf *apf)
+{
+ if (atomic_dec_and_test(&apf->used))
+ kmem_cache_free(async_pf_cache, apf);
+}
+
+static int async_pf_get_ref(struct slow_work *work)
+{
+ struct kvm_async_pf *apf =
+ container_of(work, struct kvm_async_pf, work);
+
+ atomic_inc(&apf->used);
+ return 0;
+}
+
+static void async_pf_put_ref(struct slow_work *work)
+{
+ struct kvm_async_pf *apf =
+ container_of(work, struct kvm_async_pf, work);
+
+ kvm_put_kvm(apf->vcpu->kvm);
+ async_pf_work_free(apf);
+}
+
+static void async_pf_execute(struct slow_work *work)
+{
+ struct page *page;
+ struct kvm_async_pf *apf =
+ container_of(work, struct kvm_async_pf, work);
+ wait_queue_head_t *q = &apf->vcpu->wq;
+
+ might_sleep();
+
+ down_read(&apf->mm->mmap_sem);
+ get_user_pages(current, apf->mm, apf->addr, 1, 1, 0, &page, NULL);
+ up_read(&apf->mm->mmap_sem);
+
+ spin_lock(&apf->vcpu->async_pf_lock);
+ list_add_tail(&apf->link, &apf->vcpu->async_pf_done);
+ apf->page = page;
+ spin_unlock(&apf->vcpu->async_pf_lock);
+
+ trace_kvm_async_pf_completed(apf->addr, apf->page, apf->gva);
+
+ if (waitqueue_active(q))
+ wake_up_interruptible(q);
+
+ mmdrop(apf->mm);
+}
+
+struct slow_work_ops async_pf_ops = {
+ .get_ref = async_pf_get_ref,
+ .put_ref = async_pf_put_ref,
+ .execute = async_pf_execute
+};
+
+void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
+{
+ /* cancel outstanding slow work item */
+ while (!list_empty(&vcpu->async_pf_queue)) {
+ struct kvm_async_pf *work =
+ list_entry(vcpu->async_pf_queue.next,
+ typeof(*work), queue);
+ slow_work_cancel(&work->work);
+ list_del(&work->queue);
+ if (!work->page) /* work was canceled */
+ kmem_cache_free(async_pf_cache, work);
+ }
+
+ spin_lock(&vcpu->async_pf_lock);
+ while (!list_empty(&vcpu->async_pf_done)) {
+ struct kvm_async_pf *work =
+ list_entry(vcpu->async_pf_done.next,
+ typeof(*work), link);
+ list_del(&work->link);
+ put_page(work->page);
+ kmem_cache_free(async_pf_cache, work);
+ }
+ spin_unlock(&vcpu->async_pf_lock);
+
+ vcpu->async_pf_queued = 0;
+ vcpu->async_pf_work = NULL;
+}
+
+void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
+{
+ struct kvm_async_pf *work = vcpu->async_pf_work;
+
+ if (work) {
+ vcpu->async_pf_work = NULL;
+ if (work->page == NULL) {
+ kvm_arch_inject_async_page_not_present(vcpu, work);
+ return;
+ } else {
+ spin_lock(&vcpu->async_pf_lock);
+ list_del(&work->link);
+ spin_unlock(&vcpu->async_pf_lock);
+ put_page(work->page);
+ async_pf_work_free(work);
+ list_del(&work->queue);
+ vcpu->async_pf_queued--;
+ }
+ }
+
+ if (list_empty_careful(&vcpu->async_pf_done) ||
+ !kvm_arch_can_inject_async_page_present(vcpu))
+ return;
+
+ spin_lock(&vcpu->async_pf_lock);
+ work = list_first_entry(&vcpu->async_pf_done, typeof(*work), link);
+ list_del(&work->link);
+ spin_unlock(&vcpu->async_pf_lock);
+ list_del(&work->queue);
+ vcpu->async_pf_queued--;
+
+ kvm_arch_inject_async_page_present(vcpu, work);
+
+ put_page(work->page);
+ async_pf_work_free(work);
+}
+
+int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
+ struct kvm_arch_async_pf *arch)
+{
+ struct kvm_async_pf *work;
+
+ if (vcpu->async_pf_queued >= ASYNC_PF_PER_VCPU)
+ return 0;
+
+ /* setup slow work */
+
+ /* do alloc atomic since if we are going to sleep anyway we
+ may as well sleep faulting in page */
+ work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
+ if (!work)
+ return 0;
+
+ atomic_set(&work->used, 1);
+ work->page = NULL;
+ work->vcpu = vcpu;
+ work->gva = gva;
+ work->addr = gfn_to_hva(vcpu->kvm, gfn);
+ work->arch = *arch;
+ work->mm = current->mm;
+ atomic_inc(&work->mm->mm_count);
+ kvm_get_kvm(work->vcpu->kvm);
+
+ /* this can't really happen otherwise gfn_to_pfn_async
+ would succeed */
+ if (unlikely(kvm_is_error_hva(work->addr)))
+ goto retry_sync;
+
+ slow_work_init(&work->work, &async_pf_ops);
+ if (slow_work_enqueue(&work->work) != 0)
+ goto retry_sync;
+
+ vcpu->async_pf_work = work;
+ list_add_tail(&work->queue, &vcpu->async_pf_queue);
+ vcpu->async_pf_queued++;
+ return 1;
+retry_sync:
+ kvm_put_kvm(work->vcpu->kvm);
+ mmdrop(work->mm);
+ kmem_cache_free(async_pf_cache, work);
+ return 0;
+}
+
+int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
+{
+ struct kvm_async_pf *work;
+
+ if (!list_empty(&vcpu->async_pf_done))
+ return 0;
+
+ work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
+ if (!work)
+ return -ENOMEM;
+
+ atomic_set(&work->used, 1);
+ work->page = bad_page;
+ get_page(bad_page);
+ INIT_LIST_HEAD(&work->queue); /* for list_del to work */
+
+ list_add_tail(&work->link, &vcpu->async_pf_done);
+ vcpu->async_pf_queued++;
+ return 0;
+}
+#endif
+
/*
* The vCPU has executed a HLT instruction with in-kernel mode enabled.
*/
@@ -2267,6 +2494,19 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
goto out_free_5;
}

+#ifdef CONFIG_KVM_ASYNC_PF
+ async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
+
+ if (!async_pf_cache) {
+ r = -ENOMEM;
+ goto out_free_6;
+ }
+
+ r = slow_work_register_user(THIS_MODULE);
+ if (r)
+ goto out_free;
+#endif
+
kvm_chardev_ops.owner = module;
kvm_vm_fops.owner = module;
kvm_vcpu_fops.owner = module;
@@ -2274,7 +2514,7 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
r = misc_register(&kvm_dev);
if (r) {
printk(KERN_ERR "kvm: misc device register failed\n");
- goto out_free;
+ goto out_unreg;
}

kvm_preempt_ops.sched_in = kvm_sched_in;
@@ -2284,7 +2524,13 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,

return 0;

+out_unreg:
+#ifdef CONFIG_KVM_ASYNC_PF
+ slow_work_unregister_user(THIS_MODULE);
out_free:
+ kmem_cache_destroy(async_pf_cache);
+out_free_6:
+#endif
kmem_cache_destroy(kvm_vcpu_cache);
out_free_5:
sysdev_unregister(&kvm_sysdev);
@@ -2314,6 +2560,11 @@ void kvm_exit(void)
kvm_exit_debug();
misc_deregister(&kvm_dev);
kmem_cache_destroy(kvm_vcpu_cache);
+#ifdef CONFIG_KVM_ASYNC_PF
+ if (async_pf_cache)
+ kmem_cache_destroy(async_pf_cache);
+ slow_work_unregister_user(THIS_MODULE);
+#endif
sysdev_unregister(&kvm_sysdev);
sysdev_class_unregister(&kvm_sysdev_class);
unregister_reboot_notifier(&kvm_reboot_notifier);
--
1.7.1

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