LinuxLists.cc - [PATCH v4 03/15] KVM: async_pf: Make GFN slot management generic

2021-08-15 01:03:23

Subject: [PATCH v4 03/15] KVM: async_pf: Make GFN slot management generic

It's not allowed to fire duplicate notification for same GFN on
x86 platform, with help of a hash table. This mechanism is going
to be used by arm64 and this makes the code generic and shareable
by multiple platforms.

* As this mechanism isn't needed by all platforms, a new kernel
config option (CONFIG_ASYNC_PF_SLOT) is introduced so that it
can be disabled at compiling time.

* The code is basically copied from x86 platform and the functions
are renamed to reflect the fact: (a) the input parameters are
vCPU and GFN. (b) The operations are resetting, searching, adding
and removing.

* Helper stub is also added on !CONFIG_KVM_ASYNC_PF because we're
going to use IS_ENABLED() instead of #ifdef on arm64 when the
asynchronous page fault is supported.

This is preparatory work to use the newly introduced functions on x86
platform and arm64 in subsequent patches.

Signed-off-by: Gavin Shan <[email protected]>
---
include/linux/kvm_host.h | 18 +++++++++
virt/kvm/Kconfig | 3 ++
virt/kvm/async_pf.c | 85 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 106 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a5f990f6dc35..a9685c2b2250 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -298,6 +298,9 @@ struct kvm_vcpu {

#ifdef CONFIG_KVM_ASYNC_PF
struct {
+#ifdef CONFIG_KVM_ASYNC_PF_SLOT
+ gfn_t gfns[ASYNC_PF_PER_VCPU];
+#endif
u32 queued;
struct list_head queue;
struct list_head done;
@@ -339,6 +342,13 @@ struct kvm_async_pf {
bool notpresent_injected;
};

+#ifdef CONFIG_KVM_ASYNC_PF_SLOT
+void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu);
+void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn);
+void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn);
+bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn);
+#endif
+
static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu)
{
return !list_empty_careful(&vcpu->async_pf.done);
@@ -350,6 +360,14 @@ bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
unsigned long hva, struct kvm_arch_async_pf *arch);
int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
#else
+static inline void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu) { }
+static inline void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn) { }
+static inline void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn) { }
+static inline bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+ return false;
+}
+
static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu)
{
return false;
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 62b39149b8c8..59b518c8c205 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -23,6 +23,9 @@ config KVM_MMIO
config KVM_ASYNC_PF
bool

+config KVM_ASYNC_PF_SLOT
+ bool
+
# Toggle to switch between direct notification and batch job
config KVM_ASYNC_PF_SYNC
bool
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index d145a61a046a..0d1fdb2932af 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -13,12 +13,97 @@
#include <linux/module.h>
#include <linux/mmu_context.h>
#include <linux/sched/mm.h>
+#ifdef CONFIG_KVM_ASYNC_PF_SLOT
+#include <linux/hash.h>
+#endif

#include "async_pf.h"
#include <trace/events/kvm.h>

static struct kmem_cache *async_pf_cache;

+#ifdef CONFIG_KVM_ASYNC_PF_SLOT
+static inline u32 kvm_async_pf_hash(gfn_t gfn)
+{
+ BUILD_BUG_ON(!is_power_of_2(ASYNC_PF_PER_VCPU));
+
+ return hash_32(gfn & 0xffffffff, order_base_2(ASYNC_PF_PER_VCPU));
+}
+
+static inline u32 kvm_async_pf_next_slot(u32 key)
+{
+ return (key + 1) & (ASYNC_PF_PER_VCPU - 1);
+}
+
+static u32 kvm_async_pf_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+ u32 key = kvm_async_pf_hash(gfn);
+ int i;
+
+ for (i = 0; i < ASYNC_PF_PER_VCPU &&
+ (vcpu->async_pf.gfns[key] != gfn &&
+ vcpu->async_pf.gfns[key] != ~0); i++)
+ key = kvm_async_pf_next_slot(key);
+
+ return key;
+}
+
+void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu)
+{
+ int i;
+
+ for (i = 0; i < ASYNC_PF_PER_VCPU; i++)
+ vcpu->async_pf.gfns[i] = ~0;
+}
+
+void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+ u32 key = kvm_async_pf_hash(gfn);
+
+ while (vcpu->async_pf.gfns[key] != ~0)
+ key = kvm_async_pf_next_slot(key);
+
+ vcpu->async_pf.gfns[key] = gfn;
+}
+
+void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+ u32 i, j, k;
+
+ i = j = kvm_async_pf_slot(vcpu, gfn);
+
+ if (WARN_ON_ONCE(vcpu->async_pf.gfns[i] != gfn))
+ return;
+
+ while (true) {
+ vcpu->async_pf.gfns[i] = ~0;
+
+ do {
+ j = kvm_async_pf_next_slot(j);
+ if (vcpu->async_pf.gfns[j] == ~0)
+ return;
+
+ k = kvm_async_pf_hash(vcpu->async_pf.gfns[j]);
+ /*
+ * k lies cyclically in ]i,j]
+ * | i.k.j |
+ * |....j i.k.| or |.k..j i...|
+ */
+ } while ((i <= j) ? (i < k && k <= j) : (i < k || k <= j));
+
+ vcpu->async_pf.gfns[i] = vcpu->async_pf.gfns[j];
+ i = j;
+ }
+}
+
+bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+ u32 key = kvm_async_pf_slot(vcpu, gfn);
+
+ return vcpu->async_pf.gfns[key] == gfn;
+}
+#endif /* CONFIG_KVM_ASYNC_PF_SLOT */
+
int kvm_async_pf_init(void)
{
async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
--
2.23.0

2021-11-10 17:00:35

by Eric Auger

[permalink] [raw]

Subject: Re: [PATCH v4 03/15] KVM: async_pf: Make GFN slot management generic

Hi Gavin,

On 8/15/21 2:59 AM, Gavin Shan wrote:
> It's not allowed to fire duplicate notification for same GFN on
> x86 platform, with help of a hash table. This mechanism is going
s/, with help of a hash table/this is achieved through a hash table
> to be used by arm64 and this makes the code generic and shareable
s/and this makes/.\n Turn the code generic
> by multiple platforms.
>
> * As this mechanism isn't needed by all platforms, a new kernel
> config option (CONFIG_ASYNC_PF_SLOT) is introduced so that it
> can be disabled at compiling time.
compile time
>
> * The code is basically copied from x86 platform and the functions
> are renamed to reflect the fact: (a) the input parameters are
> vCPU and GFN.
not for reset
(b) The operations are resetting, searching, adding
> and removing.
find, add, remove ops are renamed with _slot suffix
>
> * Helper stub is also added on !CONFIG_KVM_ASYNC_PF because we're
> going to use IS_ENABLED() instead of #ifdef on arm64 when the
> asynchronous page fault is supported.
>
> This is preparatory work to use the newly introduced functions on x86
> platform and arm64 in subsequent patches.
>
> Signed-off-by: Gavin Shan <[email protected]>
> ---
> include/linux/kvm_host.h | 18 +++++++++
> virt/kvm/Kconfig | 3 ++
> virt/kvm/async_pf.c | 85 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 106 insertions(+)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index a5f990f6dc35..a9685c2b2250 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -298,6 +298,9 @@ struct kvm_vcpu {
>
> #ifdef CONFIG_KVM_ASYNC_PF
> struct {
> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT
> + gfn_t gfns[ASYNC_PF_PER_VCPU];
> +#endif
> u32 queued;
> struct list_head queue;
> struct list_head done;
> @@ -339,6 +342,13 @@ struct kvm_async_pf {
> bool notpresent_injected;
> };
>
> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT
> +void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu);
this does not reset a "slot" but the whole hash table. So to me this
shouldn't be renamed with _slot suffix. reset_hash or reset_all_slots?
> +void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn);
> +void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn);
> +bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn);
> +#endif
> +
> static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu)
> {
> return !list_empty_careful(&vcpu->async_pf.done);
> @@ -350,6 +360,14 @@ bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> unsigned long hva, struct kvm_arch_async_pf *arch);
> int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
> #else
> +static inline void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu) { }
> +static inline void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn) { }
> +static inline void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn) { }
> +static inline bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
> +{
> + return false;
> +}
> +
> static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu)
> {
> return false;
> diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
> index 62b39149b8c8..59b518c8c205 100644
> --- a/virt/kvm/Kconfig
> +++ b/virt/kvm/Kconfig
> @@ -23,6 +23,9 @@ config KVM_MMIO
> config KVM_ASYNC_PF
> bool
>
> +config KVM_ASYNC_PF_SLOT
> + bool
> +
> # Toggle to switch between direct notification and batch job
> config KVM_ASYNC_PF_SYNC
> bool
> diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
> index d145a61a046a..0d1fdb2932af 100644
> --- a/virt/kvm/async_pf.c
> +++ b/virt/kvm/async_pf.c
> @@ -13,12 +13,97 @@
> #include <linux/module.h>
> #include <linux/mmu_context.h>
> #include <linux/sched/mm.h>
> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT
> +#include <linux/hash.h>
> +#endif
>
> #include "async_pf.h"
> #include <trace/events/kvm.h>
>
> static struct kmem_cache *async_pf_cache;
>
> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT
> +static inline u32 kvm_async_pf_hash(gfn_t gfn)
> +{
> + BUILD_BUG_ON(!is_power_of_2(ASYNC_PF_PER_VCPU));
> +
> + return hash_32(gfn & 0xffffffff, order_base_2(ASYNC_PF_PER_VCPU));
> +}
> +
> +static inline u32 kvm_async_pf_next_slot(u32 key)
> +{
> + return (key + 1) & (ASYNC_PF_PER_VCPU - 1);
> +}
> +
> +static u32 kvm_async_pf_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
> +{
> + u32 key = kvm_async_pf_hash(gfn);
> + int i;
> +
> + for (i = 0; i < ASYNC_PF_PER_VCPU &&
> + (vcpu->async_pf.gfns[key] != gfn &&
> + vcpu->async_pf.gfns[key] != ~0); i++)
> + key = kvm_async_pf_next_slot(key);
> +
> + return key;
> +}
> +
> +void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu)
> +{
> + int i;
> +
> + for (i = 0; i < ASYNC_PF_PER_VCPU; i++)
> + vcpu->async_pf.gfns[i] = ~0;
> +}
> +
> +void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
> +{
> + u32 key = kvm_async_pf_hash(gfn);
> +
> + while (vcpu->async_pf.gfns[key] != ~0)
> + key = kvm_async_pf_next_slot(key);
> +
> + vcpu->async_pf.gfns[key] = gfn;
> +}
> +
> +void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
> +{
> + u32 i, j, k;
> +
> + i = j = kvm_async_pf_slot(vcpu, gfn);
> +
> + if (WARN_ON_ONCE(vcpu->async_pf.gfns[i] != gfn))
> + return;
> +
> + while (true) {
> + vcpu->async_pf.gfns[i] = ~0;
> +
> + do {
> + j = kvm_async_pf_next_slot(j);
> + if (vcpu->async_pf.gfns[j] == ~0)
> + return;
> +
> + k = kvm_async_pf_hash(vcpu->async_pf.gfns[j]);
> + /*
> + * k lies cyclically in ]i,j]
> + * | i.k.j |
> + * |....j i.k.| or |.k..j i...|
> + */
> + } while ((i <= j) ? (i < k && k <= j) : (i < k || k <= j));
> +
> + vcpu->async_pf.gfns[i] = vcpu->async_pf.gfns[j];
> + i = j;
> + }
> +}
> +
> +bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
> +{
> + u32 key = kvm_async_pf_slot(vcpu, gfn);
> +
> + return vcpu->async_pf.gfns[key] == gfn;
> +}
> +#endif /* CONFIG_KVM_ASYNC_PF_SLOT */
> +
> int kvm_async_pf_init(void)
> {
> async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
>
Thanks

Eric

2021-11-10 17:02:24

by Eric Auger

[permalink] [raw]

Subject: Re: [PATCH v4 03/15] KVM: async_pf: Make GFN slot management generic

2022-01-13 07:42:40

by Gavin Shan

[permalink] [raw]

Subject: Re: [PATCH v4 03/15] KVM: async_pf: Make GFN slot management generic

Hi Eric,

On 11/11/21 1:00 AM, Eric Auger wrote:
> On 8/15/21 2:59 AM, Gavin Shan wrote:
>> It's not allowed to fire duplicate notification for same GFN on
>> x86 platform, with help of a hash table. This mechanism is going
> s/, with help of a hash table/this is achieved through a hash table
>> to be used by arm64 and this makes the code generic and shareable
> s/and this makes/.\n Turn the code generic
>> by multiple platforms.
>>
>> * As this mechanism isn't needed by all platforms, a new kernel
>> config option (CONFIG_ASYNC_PF_SLOT) is introduced so that it
>> can be disabled at compiling time.
> compile time

Ok.

>>
>> * The code is basically copied from x86 platform and the functions
>> are renamed to reflect the fact: (a) the input parameters are
>> vCPU and GFN.
> not for reset
> (b) The operations are resetting, searching, adding

Ok.

>> and removing.
> find, add, remove ops are renamed with _slot suffix

Ok. The commit log will be improved based on your suggestions in
next respin :)

>>
>> * Helper stub is also added on !CONFIG_KVM_ASYNC_PF because we're
>> going to use IS_ENABLED() instead of #ifdef on arm64 when the
>> asynchronous page fault is supported.
>>
>> This is preparatory work to use the newly introduced functions on x86
>> platform and arm64 in subsequent patches.
>>
>> Signed-off-by: Gavin Shan <[email protected]>
>> ---
>> include/linux/kvm_host.h | 18 +++++++++
>> virt/kvm/Kconfig | 3 ++
>> virt/kvm/async_pf.c | 85 ++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 106 insertions(+)
>>
>> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
>> index a5f990f6dc35..a9685c2b2250 100644
>> --- a/include/linux/kvm_host.h
>> +++ b/include/linux/kvm_host.h
>> @@ -298,6 +298,9 @@ struct kvm_vcpu {
>>
>> #ifdef CONFIG_KVM_ASYNC_PF
>> struct {
>> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT
>> + gfn_t gfns[ASYNC_PF_PER_VCPU];
>> +#endif
>> u32 queued;
>> struct list_head queue;
>> struct list_head done;
>> @@ -339,6 +342,13 @@ struct kvm_async_pf {
>> bool notpresent_injected;
>> };
>>
>> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT
>> +void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu);
> this does not reset a "slot" but the whole hash table. So to me this
> shouldn't be renamed with _slot suffix. reset_hash or reset_all_slots?

Sure, lets have kvm_async_pf_reset_all_slots() in next respin.

>> +void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn);
>> +void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn);
>> +bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn);
>> +#endif
>> +
>> static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu)
>> {
>> return !list_empty_careful(&vcpu->async_pf.done);
>> @@ -350,6 +360,14 @@ bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
>> unsigned long hva, struct kvm_arch_async_pf *arch);
>> int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
>> #else
>> +static inline void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu) { }
>> +static inline void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn) { }
>> +static inline void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn) { }
>> +static inline bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
>> +{
>> + return false;
>> +}
>> +
>> static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu)
>> {
>> return false;
>> diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
>> index 62b39149b8c8..59b518c8c205 100644
>> --- a/virt/kvm/Kconfig
>> +++ b/virt/kvm/Kconfig
>> @@ -23,6 +23,9 @@ config KVM_MMIO
>> config KVM_ASYNC_PF
>> bool
>>
>> +config KVM_ASYNC_PF_SLOT
>> + bool
>> +
>> # Toggle to switch between direct notification and batch job
>> config KVM_ASYNC_PF_SYNC
>> bool
>> diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
>> index d145a61a046a..0d1fdb2932af 100644
>> --- a/virt/kvm/async_pf.c
>> +++ b/virt/kvm/async_pf.c
>> @@ -13,12 +13,97 @@
>> #include <linux/module.h>
>> #include <linux/mmu_context.h>
>> #include <linux/sched/mm.h>
>> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT
>> +#include <linux/hash.h>
>> +#endif
>>
>> #include "async_pf.h"
>> #include <trace/events/kvm.h>
>>
>> static struct kmem_cache *async_pf_cache;
>>
>> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT
>> +static inline u32 kvm_async_pf_hash(gfn_t gfn)
>> +{
>> + BUILD_BUG_ON(!is_power_of_2(ASYNC_PF_PER_VCPU));
>> +
>> + return hash_32(gfn & 0xffffffff, order_base_2(ASYNC_PF_PER_VCPU));
>> +}
>> +
>> +static inline u32 kvm_async_pf_next_slot(u32 key)
>> +{
>> + return (key + 1) & (ASYNC_PF_PER_VCPU - 1);
>> +}
>> +
>> +static u32 kvm_async_pf_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
>> +{
>> + u32 key = kvm_async_pf_hash(gfn);
>> + int i;
>> +
>> + for (i = 0; i < ASYNC_PF_PER_VCPU &&
>> + (vcpu->async_pf.gfns[key] != gfn &&
>> + vcpu->async_pf.gfns[key] != ~0); i++)
>> + key = kvm_async_pf_next_slot(key);
>> +
>> + return key;
>> +}
>> +
>> +void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < ASYNC_PF_PER_VCPU; i++)
>> + vcpu->async_pf.gfns[i] = ~0;
>> +}
>> +
>> +void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
>> +{
>> + u32 key = kvm_async_pf_hash(gfn);
>> +
>> + while (vcpu->async_pf.gfns[key] != ~0)
>> + key = kvm_async_pf_next_slot(key);
>> +
>> + vcpu->async_pf.gfns[key] = gfn;
>> +}
>> +
>> +void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
>> +{
>> + u32 i, j, k;
>> +
>> + i = j = kvm_async_pf_slot(vcpu, gfn);
>> +
>> + if (WARN_ON_ONCE(vcpu->async_pf.gfns[i] != gfn))
>> + return;
>> +
>> + while (true) {
>> + vcpu->async_pf.gfns[i] = ~0;
>> +
>> + do {
>> + j = kvm_async_pf_next_slot(j);
>> + if (vcpu->async_pf.gfns[j] == ~0)
>> + return;
>> +
>> + k = kvm_async_pf_hash(vcpu->async_pf.gfns[j]);
>> + /*
>> + * k lies cyclically in ]i,j]
>> + * | i.k.j |
>> + * |....j i.k.| or |.k..j i...|
>> + */
>> + } while ((i <= j) ? (i < k && k <= j) : (i < k || k <= j));
>> +
>> + vcpu->async_pf.gfns[i] = vcpu->async_pf.gfns[j];
>> + i = j;
>> + }
>> +}
>> +
>> +bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
>> +{
>> + u32 key = kvm_async_pf_slot(vcpu, gfn);
>> +
>> + return vcpu->async_pf.gfns[key] == gfn;
>> +}
>> +#endif /* CONFIG_KVM_ASYNC_PF_SLOT */
>> +
>> int kvm_async_pf_init(void)
>> {
>> async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
>>

Thanks,
Gavin