linux-kernel - Re: [PATCH] KVM: ppc64: Enable ring-based dirty memory tracking

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Message-ID: <ZKJdMEnu14MxZ1NV@li-a450e7cc-27df-11b2-a85c-b5a9ac31e8ef.ibm.com>
Date:   Mon, 3 Jul 2023 11:01:28 +0530
From:   Kautuk Consul <kconsul@...ux.vnet.ibm.com>
To:     Nicholas Piggin <npiggin@...il.com>,
        Fabiano Rosas <farosas@...ux.ibm.com>, jpn@...ux.vnet.ibm.com,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...abs.org>,
        Thomas Huth <thuth@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>, gshan@...hat.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH] KVM: ppc64: Enable ring-based dirty memory tracking

Hi Everyone,

On 2023-06-08 08:34:48, Kautuk Consul wrote:
> - Enable CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL as ppc64 is weakly
>   ordered.
> - Enable CONFIG_NEED_KVM_DIRTY_RING_WITH_BITMAP because the
>   kvmppc_xive_native_set_attr is called in the context of an ioctl
>   syscall and will call kvmppc_xive_native_eq_sync for setting the
>   KVM_DEV_XIVE_EQ_SYNC attribute which will call mark_dirty_page()
>   when there isn't a running vcpu. Implemented the
>   kvm_arch_allow_write_without_running_vcpu to always return true
>   to allow mark_page_dirty_in_slot to mark the page dirty in the
>   memslot->dirty_bitmap in this case.
> - Set KVM_DIRTY_LOG_PAGE_OFFSET for the ring buffer's physical page
>   offset.
> - Implement the kvm_arch_mmu_enable_log_dirty_pt_masked function required
>   for the generic KVM code to call.
> - Add a check to kvmppc_vcpu_run_hv for checking whether the dirty
>   ring is soft full.
> - Implement the kvm_arch_flush_remote_tlbs_memslot function to support
>   the CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT config option.
> 
> On testing with live migration it was found that there is around
> 150-180 ms improvment in overall migration time with this patch.
> 
> Signed-off-by: Kautuk Consul <kconsul@...ux.vnet.ibm.com>
Can someone review this ?