On Thu, 22 Sep 2022 01:32:11 +0100,
Gavin Shan <gshan@xxxxxxxxxx> wrote:
>
> This enables the ring-based dirty memory tracking on ARM64. The
> feature is configured by CONFIG_HAVE_KVM_DIRTY_RING, detected and
> enabled by KVM_CAP_DIRTY_LOG_RING. A ring buffer is created on every
> VCPU when the feature is enabled. Each entry in the ring buffer is
> described by 'struct kvm_dirty_gfn'.
>
> A ring buffer entry is pushed when a page becomes dirty on host,
> and pulled by userspace after the ring buffer is mapped at physical
> page offset KVM_DIRTY_LOG_PAGE_OFFSET. The specific VCPU is enforced
> to exit if its ring buffer becomes softly full. Besides, the ring
> buffer can be reset by ioctl command KVM_RESET_DIRTY_RINGS to release
> those pulled ring buffer entries.
I think you can cut this message short. This description was useful
when the feature was initially merged, but this is only a "plumb the
damn thing" patch.
>
> Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> ---
> Documentation/virt/kvm/api.rst | 2 +-
> arch/arm64/include/uapi/asm/kvm.h | 1 +
> arch/arm64/kvm/Kconfig | 1 +
> arch/arm64/kvm/arm.c | 8 ++++++++
> 4 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index abd7c32126ce..19fa1ac017ed 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -8022,7 +8022,7 @@ regardless of what has actually been exposed through the CPUID leaf.
> 8.29 KVM_CAP_DIRTY_LOG_RING
> ---------------------------
>
> -:Architectures: x86
> +:Architectures: x86, arm64
> :Parameters: args[0] - size of the dirty log ring
>
> KVM is capable of tracking dirty memory using ring buffers that are
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index 316917b98707..a7a857f1784d 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -43,6 +43,7 @@
> #define __KVM_HAVE_VCPU_EVENTS
>
> #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
> +#define KVM_DIRTY_LOG_PAGE_OFFSET 64
>
> #define KVM_REG_SIZE(id) \
> (1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT))
> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> index 815cc118c675..0309b2d0f2da 100644
> --- a/arch/arm64/kvm/Kconfig
> +++ b/arch/arm64/kvm/Kconfig
> @@ -32,6 +32,7 @@ menuconfig KVM
> select KVM_VFIO
> select HAVE_KVM_EVENTFD
> select HAVE_KVM_IRQFD
> + select HAVE_KVM_DIRTY_RING
> select HAVE_KVM_MSI
> select HAVE_KVM_IRQCHIP
> select HAVE_KVM_IRQ_ROUTING
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 2ff0ef62abad..76816f8e082b 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -747,6 +747,14 @@ static int check_vcpu_requests(struct kvm_vcpu *vcpu)
>
> if (kvm_check_request(KVM_REQ_SUSPEND, vcpu))
> return kvm_vcpu_suspend(vcpu);
> +
> + if (kvm_check_request(KVM_REQ_RING_SOFT_FULL, vcpu) &&
> + kvm_dirty_ring_soft_full(&vcpu->dirty_ring)) {
> + kvm_make_request(KVM_REQ_RING_SOFT_FULL, vcpu);
> + vcpu->run->exit_reason = KVM_EXIT_DIRTY_RING_FULL;
> + trace_kvm_dirty_ring_exit(vcpu);
> + return 0;
> + }
This is *very* similar to the x86 code. Could we move it to common
code? Something like the diff below, to be for most of it squashed
into patch #1.
Thanks,
M.
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 76816f8e082b..93a16cdbe163 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -748,13 +748,8 @@ static int check_vcpu_requests(struct kvm_vcpu *vcpu)
if (kvm_check_request(KVM_REQ_SUSPEND, vcpu))
return kvm_vcpu_suspend(vcpu);
- if (kvm_check_request(KVM_REQ_RING_SOFT_FULL, vcpu) &&
- kvm_dirty_ring_soft_full(&vcpu->dirty_ring)) {
- kvm_make_request(KVM_REQ_RING_SOFT_FULL, vcpu);
- vcpu->run->exit_reason = KVM_EXIT_DIRTY_RING_FULL;
- trace_kvm_dirty_ring_exit(vcpu);
+ if (kvm_dirty_ring_check_request(vcpu))
return 0;
- }
}
return 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index eb7d0d7654bb..48f2519b1db7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10249,11 +10249,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (kvm_request_pending(vcpu)) {
/* Forbid vmenter if vcpu dirty ring is soft-full */
- if (kvm_check_request(KVM_REQ_RING_SOFT_FULL, vcpu) &&
- kvm_dirty_ring_soft_full(&vcpu->dirty_ring)) {
- kvm_make_request(KVM_REQ_RING_SOFT_FULL, vcpu);
- vcpu->run->exit_reason = KVM_EXIT_DIRTY_RING_FULL;
- trace_kvm_dirty_ring_exit(vcpu);
+ if (kvm_dirty_ring_check_request(vcpu)) {
r = 0;
goto out;
}
diff --git a/include/linux/kvm_dirty_ring.h b/include/linux/kvm_dirty_ring.h
index 8c6755981c9b..6e484220adc0 100644
--- a/include/linux/kvm_dirty_ring.h
+++ b/include/linux/kvm_dirty_ring.h
@@ -64,11 +64,6 @@ static inline void kvm_dirty_ring_free(struct kvm_dirty_ring *ring)
{
}
-static inline bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring)
-{
- return true;
-}
-
#else /* CONFIG_HAVE_KVM_DIRTY_RING */
int kvm_cpu_dirty_log_size(void);
@@ -91,7 +86,7 @@ void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, u32 slot, u64 offset);
struct page *kvm_dirty_ring_get_page(struct kvm_dirty_ring *ring, u32 offset);
void kvm_dirty_ring_free(struct kvm_dirty_ring *ring);
-bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring);
+bool kvm_dirty_ring_check_request(struct kvm_vcpu *vcpu);
#endif /* CONFIG_HAVE_KVM_DIRTY_RING */
diff --git a/virt/kvm/dirty_ring.c b/virt/kvm/dirty_ring.c
index 69c8c90d489d..436d7cded5bf 100644
--- a/virt/kvm/dirty_ring.c
+++ b/virt/kvm/dirty_ring.c
@@ -26,7 +26,7 @@ static u32 kvm_dirty_ring_used(struct kvm_dirty_ring *ring)
return READ_ONCE(ring->dirty_index) - READ_ONCE(ring->reset_index);
}
-bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring)
+static bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring)
{
return kvm_dirty_ring_used(ring) >= ring->soft_limit;
}
@@ -182,3 +182,16 @@ void kvm_dirty_ring_free(struct kvm_dirty_ring *ring)
vfree(ring->dirty_gfns);
ring->dirty_gfns = NULL;
}
+
+bool kvm_dirty_ring_check_request(struct kvm_vcpu *vcpu)
+{
+ if (kvm_check_request(KVM_REQ_RING_SOFT_FULL, vcpu) &&
+ kvm_dirty_ring_soft_full(&vcpu->dirty_ring)) {
+ kvm_make_request(KVM_REQ_RING_SOFT_FULL, vcpu);
+ vcpu->run->exit_reason = KVM_EXIT_DIRTY_RING_FULL;
+ trace_kvm_dirty_ring_exit(vcpu);
+ return true;
+ }
+
+ return false;
+}
--
Without deviation from the norm, progress is not possible.
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