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Date: Wed, 10 Nov 2021 18:03:30 +0100
From: Eric Auger <eauger@...hat.com>
To: Gavin Shan <gshan@...hat.com>, kvmarm@...ts.cs.columbia.edu
Cc: kvm@...r.kernel.org, maz@...nel.org, linux-kernel@...r.kernel.org,
shan.gavin@...il.com, Jonathan.Cameron@...wei.com,
pbonzini@...hat.com, vkuznets@...hat.com, will@...nel.org
Subject: Re: [PATCH v4 04/15] KVM: x86: Use generic async PF slot management
Hi Gavin,
On 8/15/21 2:59 AM, Gavin Shan wrote:
> This uses the generic slot management mechanism for asynchronous
Now we have moved the hash table management in the generic code, Use
this latter ...
> page fault by enabling CONFIG_KVM_ASYNC_PF_SLOT because the private
> implementation is totally duplicate to the generic one.
>
> The changes introduced by this is pretty mechanical and shouldn't
> cause any logical changes.
suggest: No functional change intended.
>
> Signed-off-by: Gavin Shan <gshan@...hat.com>
> ---
> arch/x86/include/asm/kvm_host.h | 2 -
> arch/x86/kvm/Kconfig | 1 +
> arch/x86/kvm/mmu/mmu.c | 2 +-
> arch/x86/kvm/x86.c | 86 +++------------------------------
> 4 files changed, 8 insertions(+), 83 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 974cbfb1eefe..409c1e7137cd 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -810,7 +810,6 @@ struct kvm_vcpu_arch {
>
> struct {
> bool halted;
> - gfn_t gfns[ASYNC_PF_PER_VCPU];
> struct gfn_to_hva_cache data;
> u64 msr_en_val; /* MSR_KVM_ASYNC_PF_EN */
> u64 msr_int_val; /* MSR_KVM_ASYNC_PF_INT */
> @@ -1878,7 +1877,6 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu,
> struct kvm_async_pf *work);
> void kvm_arch_async_page_present_queued(struct kvm_vcpu *vcpu);
> bool kvm_arch_can_dequeue_async_page_present(struct kvm_vcpu *vcpu);
> -extern bool kvm_find_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn);
>
> int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu);
> int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err);
> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
> index ac69894eab88..53a6ef30b6ee 100644
> --- a/arch/x86/kvm/Kconfig
> +++ b/arch/x86/kvm/Kconfig
> @@ -32,6 +32,7 @@ config KVM
> select HAVE_KVM_IRQ_ROUTING
> select HAVE_KVM_EVENTFD
> select KVM_ASYNC_PF
> + select KVM_ASYNC_PF_SLOT
> select USER_RETURN_NOTIFIER
> select KVM_MMIO
> select SCHED_INFO
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index c4f4fa23320e..cd8aaa662ac2 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -3799,7 +3799,7 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
>
> if (!prefault && kvm_can_do_async_pf(vcpu)) {
> trace_kvm_try_async_get_page(cr2_or_gpa, gfn);
> - if (kvm_find_async_pf_gfn(vcpu, gfn)) {
> + if (kvm_async_pf_find_slot(vcpu, gfn)) {
> trace_kvm_async_pf_doublefault(cr2_or_gpa, gfn);
> kvm_make_request(KVM_REQ_APF_HALT, vcpu);
> return true;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 7f35d9324b99..a5f7d6122178 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -332,13 +332,6 @@ static struct kmem_cache *kvm_alloc_emulator_cache(void)
>
> static int emulator_fix_hypercall(struct x86_emulate_ctxt *ctxt);
>
> -static inline void kvm_async_pf_hash_reset(struct kvm_vcpu *vcpu)
> -{
> - int i;
> - for (i = 0; i < ASYNC_PF_PER_VCPU; i++)
> - vcpu->arch.apf.gfns[i] = ~0;
> -}
> -
> static void kvm_on_user_return(struct user_return_notifier *urn)
> {
> unsigned slot;
> @@ -854,7 +847,7 @@ void kvm_post_set_cr0(struct kvm_vcpu *vcpu, unsigned long old_cr0, unsigned lon
> {
> if ((cr0 ^ old_cr0) & X86_CR0_PG) {
> kvm_clear_async_pf_completion_queue(vcpu);
> - kvm_async_pf_hash_reset(vcpu);
> + kvm_async_pf_reset_slot(vcpu);
> }
>
> if ((cr0 ^ old_cr0) & KVM_MMU_CR0_ROLE_BITS)
> @@ -3118,7 +3111,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
>
> if (!kvm_pv_async_pf_enabled(vcpu)) {
> kvm_clear_async_pf_completion_queue(vcpu);
> - kvm_async_pf_hash_reset(vcpu);
> + kvm_async_pf_reset_slot(vcpu);
> return 0;
> }
>
> @@ -10704,7 +10697,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
>
> vcpu->arch.pat = MSR_IA32_CR_PAT_DEFAULT;
>
> - kvm_async_pf_hash_reset(vcpu);
> + kvm_async_pf_reset_slot(vcpu);
> kvm_pmu_init(vcpu);
>
> vcpu->arch.pending_external_vector = -1;
> @@ -10828,7 +10821,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> kvmclock_reset(vcpu);
>
> kvm_clear_async_pf_completion_queue(vcpu);
> - kvm_async_pf_hash_reset(vcpu);
> + kvm_async_pf_reset_slot(vcpu);
> vcpu->arch.apf.halted = false;
>
> if (vcpu->arch.guest_fpu && kvm_mpx_supported()) {
> @@ -11737,73 +11730,6 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work)
> kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true);
> }
>
> -static inline u32 kvm_async_pf_hash_fn(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_probe(u32 key)
> -{
> - return (key + 1) & (ASYNC_PF_PER_VCPU - 1);
> -}
> -
> -static void kvm_add_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn)
> -{
> - u32 key = kvm_async_pf_hash_fn(gfn);
> -
> - while (vcpu->arch.apf.gfns[key] != ~0)
> - key = kvm_async_pf_next_probe(key);
> -
> - vcpu->arch.apf.gfns[key] = gfn;
> -}
> -
> -static u32 kvm_async_pf_gfn_slot(struct kvm_vcpu *vcpu, gfn_t gfn)
> -{
> - int i;
> - u32 key = kvm_async_pf_hash_fn(gfn);
> -
> - for (i = 0; i < ASYNC_PF_PER_VCPU &&
> - (vcpu->arch.apf.gfns[key] != gfn &&
> - vcpu->arch.apf.gfns[key] != ~0); i++)
> - key = kvm_async_pf_next_probe(key);
> -
> - return key;
> -}
> -
> -bool kvm_find_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn)
> -{
> - return vcpu->arch.apf.gfns[kvm_async_pf_gfn_slot(vcpu, gfn)] == gfn;
> -}
> -
> -static void kvm_del_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn)
> -{
> - u32 i, j, k;
> -
> - i = j = kvm_async_pf_gfn_slot(vcpu, gfn);
> -
> - if (WARN_ON_ONCE(vcpu->arch.apf.gfns[i] != gfn))
> - return;
> -
> - while (true) {
> - vcpu->arch.apf.gfns[i] = ~0;
> - do {
> - j = kvm_async_pf_next_probe(j);
> - if (vcpu->arch.apf.gfns[j] == ~0)
> - return;
> - k = kvm_async_pf_hash_fn(vcpu->arch.apf.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->arch.apf.gfns[i] = vcpu->arch.apf.gfns[j];
> - i = j;
> - }
> -}
> -
> static inline int apf_put_user_notpresent(struct kvm_vcpu *vcpu)
> {
> u32 reason = KVM_PV_REASON_PAGE_NOT_PRESENT;
> @@ -11867,7 +11793,7 @@ bool kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,
> struct x86_exception fault;
>
> trace_kvm_async_pf_not_present(work->arch.token, work->cr2_or_gpa);
> - kvm_add_async_pf_gfn(vcpu, work->arch.gfn);
> + kvm_async_pf_add_slot(vcpu, work->arch.gfn);
>
> if (kvm_can_deliver_async_pf(vcpu) &&
> !apf_put_user_notpresent(vcpu)) {
> @@ -11904,7 +11830,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
> if (work->wakeup_all)
> work->arch.token = ~0; /* broadcast wakeup */
> else
> - kvm_del_async_pf_gfn(vcpu, work->arch.gfn);
> + kvm_async_pf_remove_slot(vcpu, work->arch.gfn);
> trace_kvm_async_pf_ready(work->arch.token, work->cr2_or_gpa);
>
> if ((work->wakeup_all || work->notpresent_injected) &&
>
Looks good to me
Eric
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