From: Marc Zyngier <maz@kernel.org>
To: Yoan Picchi <yoan.picchi@arm.com>
Cc: james.morse@arm.com, julien.thierry.kdev@gmail.com,
suzuki.poulose@arm.com, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, catalin.marinas@arm.com,
will@kernel.org
Subject: Re: [PATCH 3/7] KVM: arm64: Add cached_page_invalidated counter for kvm_stat
Date: Tue, 23 Mar 2021 17:17:53 +0000 [thread overview]
Message-ID: <87r1k5kcvy.wl-maz@kernel.org> (raw)
In-Reply-To: <20210319161711.24972-4-yoan.picchi@arm.com>
On Fri, 19 Mar 2021 16:17:07 +0000,
Yoan Picchi <yoan.picchi@arm.com> wrote:
>
> Add some counter for when a dpage get invalidated. The counter isn't
> in the function that actually do it though because it doesn't have
> either a kvm or vcpu argument, so we would have no way to access the
> counters. For this reason, the counter have been added to the calling
> functions instead.
>
> Signed-off-by: Yoan Picchi <yoan.picchi@arm.com>
> ---
> arch/arm64/include/asm/kvm_host.h | 1 +
> arch/arm64/kvm/guest.c | 1 +
> arch/arm64/kvm/mmu.c | 5 ++++-
> 3 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 863603285..3609aa89d 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -547,6 +547,7 @@ static inline bool __vcpu_write_sys_reg_to_cpu(u64 val, int reg)
>
> struct kvm_vm_stat {
> ulong remote_tlb_flush;
> + ulong cached_page_invalidated;
> };
>
> struct kvm_vcpu_stat {
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 1029976ca..f6b1f0b63 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -41,6 +41,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
> VCPU_STAT("regular_page_mapped", regular_page_mapped),
> VCPU_STAT("huge_page_mapped", huge_page_mapped),
> VM_STAT("remote_tlb_flush", remote_tlb_flush),
> + VM_STAT("cached_page_invalidated", cached_page_invalidated),
> VCPU_STAT("exits", exits),
> VCPU_STAT("halt_poll_success_ns", halt_poll_success_ns),
> VCPU_STAT("halt_poll_fail_ns", halt_poll_fail_ns),
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 55d7fe63b..d6ddf5ab8 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -893,8 +893,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
> if (writable)
> prot |= KVM_PGTABLE_PROT_W;
>
> - if (fault_status != FSC_PERM && !device)
> + if (fault_status != FSC_PERM && !device) {
> clean_dcache_guest_page(pfn, vma_pagesize);
> + kvm->stat.cached_page_invalidated++;
> + }
>
> if (exec_fault) {
> prot |= KVM_PGTABLE_PROT_X;
> @@ -1166,6 +1168,7 @@ int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
> * just like a translation fault and clean the cache to the PoC.
> */
> clean_dcache_guest_page(pfn, PAGE_SIZE);
> + kvm->stat.cached_page_invalidated++;
> handle_hva_to_gpa(kvm, hva, end, &kvm_set_spte_handler, &pfn);
> return 0;
> }
Given that PoC flushing is only done on translation fault, what are
the odds that this would report a different number than that of
translation faults (assuming it was actually implemented)?
It is also interesting that you attribute the same cost to flushing a
4kB page or a 1GB block. And what does this mean when either FWB or
IDC are available?
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2021-03-23 17:19 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 16:17 [PATCH 0/7] KVM: arm64: add more event counters for kvm_stat Yoan Picchi
2021-03-19 16:17 ` [PATCH 1/7] KVM: arm64: Add two page mapping " Yoan Picchi
2021-03-23 11:52 ` Keqian Zhu
2021-03-23 17:03 ` Marc Zyngier
2021-03-19 16:17 ` [PATCH 2/7] KVM: arm64: Add remote_tlb_flush counter " Yoan Picchi
2021-03-23 17:12 ` Marc Zyngier
2021-03-19 16:17 ` [PATCH 3/7] KVM: arm64: Add cached_page_invalidated " Yoan Picchi
2021-03-23 17:17 ` Marc Zyngier [this message]
2021-03-19 16:17 ` [PATCH 4/7] KVM: arm64: Add flush_all_cache_lines " Yoan Picchi
2021-03-23 17:22 ` Marc Zyngier
2021-03-19 16:17 ` [PATCH 5/7] KVM: arm64: Add memory_slot_unmaped " Yoan Picchi
2021-03-23 17:33 ` Marc Zyngier
2021-03-19 16:17 ` [PATCH 6/7] KVM: arm64: Add stage2_unmap_vm " Yoan Picchi
2021-03-23 17:33 ` Marc Zyngier
2021-03-19 16:17 ` [PATCH 7/7] KVM: arm64: Add irq_inject " Yoan Picchi
2021-03-23 17:37 ` Marc Zyngier
2021-03-23 17:53 ` Yoan Picchi
2021-03-23 18:36 ` Marc Zyngier
2021-03-23 18:04 ` [PATCH 0/7] KVM: arm64: add more event counters " Marc Zyngier
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