From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Xu <peterx@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH RFC 00/15] KVM: Dirty ring interface
Date: Sat, 30 Nov 2019 09:29:42 +0100 [thread overview]
Message-ID: <b8f28d8c-2486-2d66-04fd-a2674b598cfd@redhat.com> (raw)
In-Reply-To: <20191129213505.18472-1-peterx@redhat.com>
Hi Peter,
thanks for the RFC! Just a couple comments before I look at the series
(for which I don't expect many surprises).
On 29/11/19 22:34, Peter Xu wrote:
> I marked this series as RFC because I'm at least uncertain on this
> change of vcpu_enter_guest():
>
> if (kvm_check_request(KVM_REQ_DIRTY_RING_FULL, vcpu)) {
> vcpu->run->exit_reason = KVM_EXIT_DIRTY_RING_FULL;
> /*
> * If this is requested, it means that we've
> * marked the dirty bit in the dirty ring BUT
> * we've not written the date. Do it now.
> */
> r = kvm_emulate_instruction(vcpu, 0);
> r = r >= 0 ? 0 : r;
> goto out;
> }
This is not needed, it will just be a false negative (dirty page that
actually isn't dirty). The dirty bit will be cleared when userspace
resets the ring buffer; then the instruction will be executed again and
mark the page dirty again. Since ring full is not a common condition,
it's not a big deal.
> I did a kvm_emulate_instruction() when dirty ring reaches softlimit
> and want to exit to userspace, however I'm not really sure whether
> there could have any side effect. I'd appreciate any comment of
> above, or anything else.
>
> Tests
> ===========
>
> I wanted to continue work on the QEMU part, but after I noticed that
> the interface might still prone to change, I posted this series first.
> However to make sure it's at least working, I've provided unit tests
> together with the series. The unit tests should be able to test the
> series in at least three major paths:
>
> (1) ./dirty_log_test -M dirty-ring
>
> This tests async ring operations: this should be the major work
> mode for the dirty ring interface, say, when the kernel is
> queuing more data, the userspace is collecting too. Ring can
> hardly reaches full when working like this, because in most
> cases the collection could be fast.
>
> (2) ./dirty_log_test -M dirty-ring -c 1024
>
> This set the ring size to be very small so that ring soft-full
> always triggers (soft-full is a soft limit of the ring state,
> when the dirty ring reaches the soft limit it'll do a userspace
> exit and let the userspace to collect the data).
>
> (3) ./dirty_log_test -M dirty-ring-wait-queue
>
> This sololy test the extreme case where ring is full. When the
> ring is completely full, the thread (no matter vcpu or not) will
> be put onto a per-vm waitqueue, and KVM_RESET_DIRTY_RINGS will
> wake the threads up (assuming until which the ring will not be
> full any more).
One question about this testcase: why does the task get into
uninterruptible wait?
Paolo
>
> Thanks,
>
> Cao, Lei (2):
> KVM: Add kvm/vcpu argument to mark_dirty_page_in_slot
> KVM: X86: Implement ring-based dirty memory tracking
>
> Paolo Bonzini (1):
> KVM: Move running VCPU from ARM to common code
>
> Peter Xu (12):
> KVM: Add build-time error check on kvm_run size
> KVM: Implement ring-based dirty memory tracking
> KVM: Make dirty ring exclusive to dirty bitmap log
> KVM: Introduce dirty ring wait queue
> KVM: selftests: Always clear dirty bitmap after iteration
> KVM: selftests: Sync uapi/linux/kvm.h to tools/
> KVM: selftests: Use a single binary for dirty/clear log test
> KVM: selftests: Introduce after_vcpu_run hook for dirty log test
> KVM: selftests: Add dirty ring buffer test
> KVM: selftests: Let dirty_log_test async for dirty ring test
> KVM: selftests: Add "-c" parameter to dirty log test
> KVM: selftests: Test dirty ring waitqueue
>
> Documentation/virt/kvm/api.txt | 116 +++++
> arch/arm/include/asm/kvm_host.h | 2 -
> arch/arm64/include/asm/kvm_host.h | 2 -
> arch/x86/include/asm/kvm_host.h | 5 +
> arch/x86/include/uapi/asm/kvm.h | 1 +
> arch/x86/kvm/Makefile | 3 +-
> arch/x86/kvm/mmu/mmu.c | 6 +
> arch/x86/kvm/vmx/vmx.c | 7 +
> arch/x86/kvm/x86.c | 12 +
> include/linux/kvm_dirty_ring.h | 67 +++
> include/linux/kvm_host.h | 37 ++
> include/linux/kvm_types.h | 1 +
> include/uapi/linux/kvm.h | 36 ++
> tools/include/uapi/linux/kvm.h | 47 ++
> tools/testing/selftests/kvm/Makefile | 2 -
> .../selftests/kvm/clear_dirty_log_test.c | 2 -
> tools/testing/selftests/kvm/dirty_log_test.c | 452 ++++++++++++++++--
> .../testing/selftests/kvm/include/kvm_util.h | 6 +
> tools/testing/selftests/kvm/lib/kvm_util.c | 103 ++++
> .../selftests/kvm/lib/kvm_util_internal.h | 5 +
> virt/kvm/arm/arm.c | 29 --
> virt/kvm/arm/perf.c | 6 +-
> virt/kvm/arm/vgic/vgic-mmio.c | 15 +-
> virt/kvm/dirty_ring.c | 156 ++++++
> virt/kvm/kvm_main.c | 315 +++++++++++-
> 25 files changed, 1329 insertions(+), 104 deletions(-)
> create mode 100644 include/linux/kvm_dirty_ring.h
> delete mode 100644 tools/testing/selftests/kvm/clear_dirty_log_test.c
> create mode 100644 virt/kvm/dirty_ring.c
>
next prev parent reply other threads:[~2019-11-30 8:30 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-29 21:34 [PATCH RFC 00/15] KVM: Dirty ring interface Peter Xu
2019-11-29 21:34 ` [PATCH RFC 01/15] KVM: Move running VCPU from ARM to common code Peter Xu
2019-12-03 19:01 ` Sean Christopherson
2019-12-04 9:42 ` Paolo Bonzini
2019-12-09 22:05 ` Peter Xu
2019-11-29 21:34 ` [PATCH RFC 02/15] KVM: Add kvm/vcpu argument to mark_dirty_page_in_slot Peter Xu
2019-12-02 19:32 ` Sean Christopherson
2019-12-02 20:49 ` Peter Xu
2019-11-29 21:34 ` [PATCH RFC 03/15] KVM: Add build-time error check on kvm_run size Peter Xu
2019-12-02 19:30 ` Sean Christopherson
2019-12-02 20:53 ` Peter Xu
2019-12-02 22:19 ` Sean Christopherson
2019-12-02 22:40 ` Peter Xu
2019-12-03 5:50 ` Sean Christopherson
2019-12-03 13:41 ` Paolo Bonzini
2019-12-03 17:04 ` Peter Xu
2019-11-29 21:34 ` [PATCH RFC 04/15] KVM: Implement ring-based dirty memory tracking Peter Xu
2019-12-02 20:10 ` Sean Christopherson
2019-12-02 21:16 ` Peter Xu
2019-12-02 21:50 ` Sean Christopherson
2019-12-02 23:09 ` Peter Xu
2019-12-03 13:48 ` Paolo Bonzini
2019-12-03 18:46 ` Sean Christopherson
2019-12-04 10:05 ` Paolo Bonzini
2019-12-07 0:29 ` Sean Christopherson
2019-12-09 9:37 ` Paolo Bonzini
2019-12-09 21:54 ` Peter Xu
2019-12-10 10:07 ` Paolo Bonzini
2019-12-10 15:52 ` Peter Xu
2019-12-10 17:09 ` Paolo Bonzini
2019-12-15 17:21 ` Peter Xu
2019-12-16 10:08 ` Paolo Bonzini
2019-12-16 18:54 ` Peter Xu
2019-12-17 9:01 ` Paolo Bonzini
2019-12-17 16:24 ` Peter Xu
2019-12-17 16:28 ` Paolo Bonzini
2019-12-18 21:58 ` Peter Xu
2019-12-18 22:24 ` Sean Christopherson
2019-12-18 22:37 ` Paolo Bonzini
2019-12-18 22:49 ` Peter Xu
2019-12-17 2:28 ` Tian, Kevin
2019-12-17 16:18 ` Alex Williamson
2019-12-17 16:30 ` Paolo Bonzini
2019-12-18 0:29 ` Tian, Kevin
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19D645E5F@SHSMSX104.ccr.corp.intel.com>
2019-12-17 5:17 ` Tian, Kevin
2019-12-17 5:25 ` Yan Zhao
2019-12-17 16:24 ` Alex Williamson
2019-12-03 19:13 ` Sean Christopherson
2019-12-04 10:14 ` Paolo Bonzini
2019-12-04 14:33 ` Sean Christopherson
2019-12-04 10:38 ` Jason Wang
2019-12-04 11:04 ` Paolo Bonzini
2019-12-04 19:52 ` Peter Xu
2019-12-05 6:51 ` Jason Wang
2019-12-05 12:08 ` Peter Xu
2019-12-05 13:12 ` Jason Wang
2019-12-10 13:25 ` Michael S. Tsirkin
2019-12-10 13:31 ` Paolo Bonzini
2019-12-10 16:02 ` Peter Xu
2019-12-10 21:53 ` Michael S. Tsirkin
2019-12-11 9:05 ` Paolo Bonzini
2019-12-11 13:04 ` Michael S. Tsirkin
2019-12-11 14:54 ` Peter Xu
2019-12-10 21:48 ` Michael S. Tsirkin
2019-12-11 12:53 ` Michael S. Tsirkin
2019-12-11 14:14 ` Paolo Bonzini
2019-12-11 20:59 ` Peter Xu
2019-12-11 22:57 ` Michael S. Tsirkin
2019-12-12 0:08 ` Paolo Bonzini
2019-12-12 7:36 ` Michael S. Tsirkin
2019-12-12 8:12 ` Paolo Bonzini
2019-12-12 10:38 ` Michael S. Tsirkin
2019-12-15 17:33 ` Peter Xu
2019-12-16 9:47 ` Michael S. Tsirkin
2019-12-16 15:07 ` Peter Xu
2019-12-16 15:33 ` Michael S. Tsirkin
2019-12-16 15:47 ` Peter Xu
2019-12-11 17:24 ` Christophe de Dinechin
2019-12-13 20:23 ` Peter Xu
2019-12-14 7:57 ` Paolo Bonzini
2019-12-14 16:26 ` Peter Xu
2019-12-16 9:29 ` Paolo Bonzini
2019-12-16 15:26 ` Peter Xu
2019-12-16 15:31 ` Paolo Bonzini
2019-12-16 15:43 ` Peter Xu
2019-12-17 12:16 ` Christophe de Dinechin
2019-12-17 12:19 ` Paolo Bonzini
2019-12-17 15:38 ` Peter Xu
2019-12-17 16:31 ` Paolo Bonzini
2019-12-17 16:42 ` Peter Xu
2019-12-17 16:48 ` Paolo Bonzini
2019-12-17 19:41 ` Peter Xu
2019-12-18 0:33 ` Paolo Bonzini
2019-12-18 16:32 ` Peter Xu
2019-12-18 16:41 ` Paolo Bonzini
2019-12-20 18:19 ` Peter Xu
2019-11-29 21:34 ` [PATCH RFC 05/15] KVM: Make dirty ring exclusive to dirty bitmap log Peter Xu
2019-11-29 21:34 ` [PATCH RFC 06/15] KVM: Introduce dirty ring wait queue Peter Xu
2019-11-29 21:34 ` [PATCH RFC 07/15] KVM: X86: Implement ring-based dirty memory tracking Peter Xu
2019-11-29 21:34 ` [PATCH RFC 08/15] KVM: selftests: Always clear dirty bitmap after iteration Peter Xu
2019-11-29 21:34 ` [PATCH RFC 09/15] KVM: selftests: Sync uapi/linux/kvm.h to tools/ Peter Xu
2019-11-29 21:35 ` [PATCH RFC 10/15] KVM: selftests: Use a single binary for dirty/clear log test Peter Xu
2019-11-29 21:35 ` [PATCH RFC 11/15] KVM: selftests: Introduce after_vcpu_run hook for dirty " Peter Xu
2019-11-29 21:35 ` [PATCH RFC 12/15] KVM: selftests: Add dirty ring buffer test Peter Xu
2019-11-29 21:35 ` [PATCH RFC 13/15] KVM: selftests: Let dirty_log_test async for dirty ring test Peter Xu
2019-11-29 21:35 ` [PATCH RFC 14/15] KVM: selftests: Add "-c" parameter to dirty log test Peter Xu
2019-11-29 21:35 ` [PATCH RFC 15/15] KVM: selftests: Test dirty ring waitqueue Peter Xu
2019-11-30 8:29 ` Paolo Bonzini [this message]
2019-12-02 2:13 ` [PATCH RFC 00/15] KVM: Dirty ring interface Peter Xu
2019-12-03 13:59 ` Paolo Bonzini
2019-12-05 19:30 ` Peter Xu
2019-12-05 19:59 ` Paolo Bonzini
2019-12-05 20:52 ` Peter Xu
2019-12-02 20:21 ` Sean Christopherson
2019-12-02 20:43 ` Peter Xu
2019-12-04 10:39 ` Jason Wang
2019-12-04 19:33 ` Peter Xu
2019-12-05 6:49 ` Jason Wang
2019-12-11 13:41 ` Christophe de Dinechin
2019-12-11 14:16 ` Paolo Bonzini
2019-12-11 17:15 ` Peter Xu
-- strict thread matches above, loose matches on Subject: below --
2019-11-29 21:33 Peter Xu
2019-11-29 21:32 Peter Xu
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