From: Paolo Bonzini <pbonzini@redhat.com>
To: Marc Zyngier <maz@kernel.org>, Oliver Upton <oliver.upton@linux.dev>
Cc: kvm@vger.kernel.org, linux-doc@vger.kernel.org,
catalin.marinas@arm.com, linux-kselftest@vger.kernel.org,
bgardon@google.com, shuah@kernel.org,
kvmarm@lists.cs.columbia.edu, corbet@lwn.net, will@kernel.org,
shan.gavin@gmail.com, drjones@redhat.com, zhenyzha@redhat.com,
dmatlack@google.com, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 1/5] KVM: arm64: Enable ring-based dirty memory tracking
Date: Fri, 26 Aug 2022 12:58:08 +0200 [thread overview]
Message-ID: <99364855-b4e9-8a69-e1ca-ed09d103e4c8@redhat.com> (raw)
In-Reply-To: <87a67uwve8.wl-maz@kernel.org>
On 8/23/22 22:35, Marc Zyngier wrote:
>> Heh, yeah I need to get that out the door. I'll also note that Gavin's
>> changes are still relevant without that series, as we do write unprotect
>> in parallel at PTE granularity after commit f783ef1c0e82 ("KVM: arm64:
>> Add fast path to handle permission relaxation during dirty logging").
>
> Ah, true. Now if only someone could explain how the whole
> producer-consumer thing works without a trace of a barrier, that'd be
> great...
Do you mean this?
void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, u32 slot, u64 offset)
{
struct kvm_dirty_gfn *entry;
/* It should never get full */
WARN_ON_ONCE(kvm_dirty_ring_full(ring));
entry = &ring->dirty_gfns[ring->dirty_index & (ring->size - 1)];
entry->slot = slot;
entry->offset = offset;
/*
* Make sure the data is filled in before we publish this to
* the userspace program. There's no paired kernel-side reader.
*/
smp_wmb();
kvm_dirty_gfn_set_dirtied(entry);
ring->dirty_index++;
trace_kvm_dirty_ring_push(ring, slot, offset);
}
The matching smp_rmb() is in userspace.
Paolo
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Marc Zyngier <maz@kernel.org>, Oliver Upton <oliver.upton@linux.dev>
Cc: Gavin Shan <gshan@redhat.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kselftest@vger.kernel.org, peterx@redhat.com,
corbet@lwn.net, james.morse@arm.com, alexandru.elisei@arm.com,
suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org,
shuah@kernel.org, seanjc@google.com, drjones@redhat.com,
dmatlack@google.com, bgardon@google.com, ricarkol@google.com,
zhenyzha@redhat.com, shan.gavin@gmail.com
Subject: Re: [PATCH v1 1/5] KVM: arm64: Enable ring-based dirty memory tracking
Date: Fri, 26 Aug 2022 12:58:08 +0200 [thread overview]
Message-ID: <99364855-b4e9-8a69-e1ca-ed09d103e4c8@redhat.com> (raw)
In-Reply-To: <87a67uwve8.wl-maz@kernel.org>
On 8/23/22 22:35, Marc Zyngier wrote:
>> Heh, yeah I need to get that out the door. I'll also note that Gavin's
>> changes are still relevant without that series, as we do write unprotect
>> in parallel at PTE granularity after commit f783ef1c0e82 ("KVM: arm64:
>> Add fast path to handle permission relaxation during dirty logging").
>
> Ah, true. Now if only someone could explain how the whole
> producer-consumer thing works without a trace of a barrier, that'd be
> great...
Do you mean this?
void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, u32 slot, u64 offset)
{
struct kvm_dirty_gfn *entry;
/* It should never get full */
WARN_ON_ONCE(kvm_dirty_ring_full(ring));
entry = &ring->dirty_gfns[ring->dirty_index & (ring->size - 1)];
entry->slot = slot;
entry->offset = offset;
/*
* Make sure the data is filled in before we publish this to
* the userspace program. There's no paired kernel-side reader.
*/
smp_wmb();
kvm_dirty_gfn_set_dirtied(entry);
ring->dirty_index++;
trace_kvm_dirty_ring_push(ring, slot, offset);
}
The matching smp_rmb() is in userspace.
Paolo
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Marc Zyngier <maz@kernel.org>, Oliver Upton <oliver.upton@linux.dev>
Cc: Gavin Shan <gshan@redhat.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kselftest@vger.kernel.org, peterx@redhat.com,
corbet@lwn.net, james.morse@arm.com, alexandru.elisei@arm.com,
suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org,
shuah@kernel.org, seanjc@google.com, drjones@redhat.com,
dmatlack@google.com, bgardon@google.com, ricarkol@google.com,
zhenyzha@redhat.com, shan.gavin@gmail.com
Subject: Re: [PATCH v1 1/5] KVM: arm64: Enable ring-based dirty memory tracking
Date: Fri, 26 Aug 2022 12:58:08 +0200 [thread overview]
Message-ID: <99364855-b4e9-8a69-e1ca-ed09d103e4c8@redhat.com> (raw)
In-Reply-To: <87a67uwve8.wl-maz@kernel.org>
On 8/23/22 22:35, Marc Zyngier wrote:
>> Heh, yeah I need to get that out the door. I'll also note that Gavin's
>> changes are still relevant without that series, as we do write unprotect
>> in parallel at PTE granularity after commit f783ef1c0e82 ("KVM: arm64:
>> Add fast path to handle permission relaxation during dirty logging").
>
> Ah, true. Now if only someone could explain how the whole
> producer-consumer thing works without a trace of a barrier, that'd be
> great...
Do you mean this?
void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, u32 slot, u64 offset)
{
struct kvm_dirty_gfn *entry;
/* It should never get full */
WARN_ON_ONCE(kvm_dirty_ring_full(ring));
entry = &ring->dirty_gfns[ring->dirty_index & (ring->size - 1)];
entry->slot = slot;
entry->offset = offset;
/*
* Make sure the data is filled in before we publish this to
* the userspace program. There's no paired kernel-side reader.
*/
smp_wmb();
kvm_dirty_gfn_set_dirtied(entry);
ring->dirty_index++;
trace_kvm_dirty_ring_push(ring, slot, offset);
}
The matching smp_rmb() is in userspace.
Paolo
next prev parent reply other threads:[~2022-08-26 10:58 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-19 0:55 [PATCH v1 0/5] KVM: arm64: Enable ring-based dirty memory tracking Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` [PATCH v1 1/5] " Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 8:00 ` Marc Zyngier
2022-08-19 8:00 ` Marc Zyngier
2022-08-19 8:00 ` Marc Zyngier
2022-08-22 1:58 ` Gavin Shan
2022-08-22 1:58 ` Gavin Shan
2022-08-22 18:55 ` Peter Xu
2022-08-22 18:55 ` Peter Xu
2022-08-22 18:55 ` Peter Xu
2022-08-23 3:19 ` Gavin Shan
2022-08-23 3:19 ` Gavin Shan
2022-08-23 3:19 ` Gavin Shan
2022-08-22 21:42 ` Marc Zyngier
2022-08-22 21:42 ` Marc Zyngier
2022-08-22 21:42 ` Marc Zyngier
2022-08-23 5:22 ` Gavin Shan
2022-08-23 5:22 ` Gavin Shan
2022-08-23 5:22 ` Gavin Shan
2022-08-23 13:58 ` Peter Xu
2022-08-23 13:58 ` Peter Xu
2022-08-23 13:58 ` Peter Xu
2022-08-23 19:17 ` Marc Zyngier
2022-08-23 19:17 ` Marc Zyngier
2022-08-23 19:17 ` Marc Zyngier
2022-08-23 21:20 ` Peter Xu
2022-08-23 21:20 ` Peter Xu
2022-08-23 21:20 ` Peter Xu
2022-08-23 22:47 ` Marc Zyngier
2022-08-23 22:47 ` Marc Zyngier
2022-08-23 22:47 ` Marc Zyngier
2022-08-23 23:19 ` Peter Xu
2022-08-23 23:19 ` Peter Xu
2022-08-23 23:19 ` Peter Xu
2022-08-24 14:45 ` Marc Zyngier
2022-08-24 14:45 ` Marc Zyngier
2022-08-24 14:45 ` Marc Zyngier
2022-08-24 16:21 ` Peter Xu
2022-08-24 16:21 ` Peter Xu
2022-08-24 16:21 ` Peter Xu
2022-08-24 20:57 ` Marc Zyngier
2022-08-24 20:57 ` Marc Zyngier
2022-08-24 20:57 ` Marc Zyngier
2022-08-26 6:05 ` Gavin Shan
2022-08-26 6:05 ` Gavin Shan
2022-08-26 6:05 ` Gavin Shan
2022-08-26 10:50 ` Paolo Bonzini
2022-08-26 10:50 ` Paolo Bonzini
2022-08-26 10:50 ` Paolo Bonzini
2022-08-26 15:49 ` Marc Zyngier
2022-08-26 15:49 ` Marc Zyngier
2022-08-26 15:49 ` Marc Zyngier
2022-08-27 8:27 ` Paolo Bonzini
2022-08-27 8:27 ` Paolo Bonzini
2022-08-27 8:27 ` Paolo Bonzini
2022-08-29 10:27 ` Paolo Bonzini
2022-08-23 14:44 ` Oliver Upton
2022-08-23 14:44 ` Oliver Upton
2022-08-23 14:44 ` Oliver Upton
2022-08-23 20:35 ` Marc Zyngier
2022-08-23 20:35 ` Marc Zyngier
2022-08-23 20:35 ` Marc Zyngier
2022-08-26 10:58 ` Paolo Bonzini [this message]
2022-08-26 10:58 ` Paolo Bonzini
2022-08-26 10:58 ` Paolo Bonzini
2022-08-26 15:28 ` Marc Zyngier
2022-08-26 15:28 ` Marc Zyngier
2022-08-26 15:28 ` Marc Zyngier
2022-08-30 14:42 ` Peter Xu
2022-08-30 14:42 ` Peter Xu
2022-08-30 14:42 ` Peter Xu
2022-09-02 0:19 ` Paolo Bonzini
2022-09-02 0:19 ` Paolo Bonzini
2022-09-02 0:19 ` Paolo Bonzini
2022-08-19 0:55 ` [PATCH v1 2/5] KVM: selftests: Use host page size to map ring buffer in dirty_log_test Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` [PATCH v1 3/5] KVM: selftests: Dirty host pages " Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 5:28 ` Andrew Jones
2022-08-19 5:28 ` Andrew Jones
2022-08-19 5:28 ` Andrew Jones
2022-08-22 6:29 ` Gavin Shan
2022-08-22 6:29 ` Gavin Shan
2022-08-23 3:09 ` Gavin Shan
2022-08-23 3:09 ` Gavin Shan
2022-08-23 3:09 ` Gavin Shan
2022-08-19 0:56 ` [PATCH v1 4/5] KVM: selftests: Clear dirty ring states between two modes " Gavin Shan
2022-08-19 0:56 ` Gavin Shan
2022-08-19 0:56 ` Gavin Shan
2022-08-19 0:56 ` [PATCH v1 5/5] KVM: selftests: Automate choosing dirty ring size " Gavin Shan
2022-08-19 0:56 ` Gavin Shan
2022-08-19 0:56 ` Gavin Shan
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