kvmarm.lists.cs.columbia.edu archive mirror
 help / color / mirror / Atom feed
From: Paolo Bonzini <pbonzini@redhat.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kvm@vger.kernel.org, catalin.marinas@arm.com,
	andrew.jones@linux.dev, will@kernel.org, shan.gavin@gmail.com,
	bgardon@google.com, dmatlack@google.com, zhenyzha@redhat.com,
	shuah@kernel.org, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 5/6] KVM: selftests: dirty-log: Upgrade dirty_gfn_set_collected() to store-release
Date: Thu, 22 Sep 2022 23:38:58 +0200	[thread overview]
Message-ID: <CABgObfbtVAM3t2WC6-8-fLdQZTs6B5Xf2-CZ4oWdJMzXNFWy_g@mail.gmail.com> (raw)
In-Reply-To: <20220922170133.2617189-6-maz@kernel.org>

On Thu, Sep 22, 2022 at 7:02 PM Marc Zyngier <maz@kernel.org> wrote:
> To make sure that all the writes to the log marking the entries
> as being in need of reset are observed in order, use a
> smp_store_release() when updating the log entry flags.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>

You also need a load-acquire on the load of gfn->flags in
dirty_gfn_is_dirtied. Otherwise reading cur->slot or cur->offset might
see a stale value.

Paolo

> ---
>  tools/testing/selftests/kvm/dirty_log_test.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
> index 9c883c94d478..3d29f4bf4f9c 100644
> --- a/tools/testing/selftests/kvm/dirty_log_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_test.c
> @@ -17,6 +17,7 @@
>  #include <linux/bitmap.h>
>  #include <linux/bitops.h>
>  #include <linux/atomic.h>
> +#include <asm/barrier.h>
>
>  #include "kvm_util.h"
>  #include "test_util.h"
> @@ -284,7 +285,7 @@ static inline bool dirty_gfn_is_dirtied(struct kvm_dirty_gfn *gfn)
>
>  static inline void dirty_gfn_set_collected(struct kvm_dirty_gfn *gfn)
>  {
> -       gfn->flags = KVM_DIRTY_GFN_F_RESET;
> +       smp_store_release(&gfn->flags, KVM_DIRTY_GFN_F_RESET);
>  }
>
>  static uint32_t dirty_ring_collect_one(struct kvm_dirty_gfn *dirty_gfns,
> --
> 2.34.1
>

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

  reply	other threads:[~2022-09-22 21:39 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-22 17:01 [PATCH 0/6] KVM: Fix dirty-ring ordering on weakly ordered architectures Marc Zyngier
2022-09-22 17:01 ` [PATCH 1/6] KVM: Use acquire/release semantics when accessing dirty ring GFN state Marc Zyngier
2022-09-22 21:38   ` Peter Xu
2022-09-22 23:46     ` Gavin Shan
2022-09-23 14:40       ` Marc Zyngier
2022-09-23 14:19     ` Marc Zyngier
2022-09-23 14:22       ` Paolo Bonzini
2022-09-22 17:01 ` [PATCH 2/6] KVM: Add KVM_CAP_DIRTY_LOG_RING_ORDERED capability and config option Marc Zyngier
2022-09-22 21:48   ` Peter Xu
2022-09-23  0:04     ` Gavin Shan
2022-09-23 14:28     ` Marc Zyngier
2022-09-23 18:26       ` Peter Xu
2022-09-23 21:23         ` Paolo Bonzini
2022-09-23 22:34           ` Peter Xu
2022-09-24  8:51         ` Marc Zyngier
2022-09-24 11:26           ` Marc Zyngier
2022-09-24 13:22             ` Peter Xu
2022-09-24 18:57               ` Marc Zyngier
2022-09-25 23:17                 ` Gavin Shan
2022-09-22 17:01 ` [PATCH 3/6] KVM: x86: Select CONFIG_HAVE_KVM_DIRTY_RING_ORDERED Marc Zyngier
2022-09-23 22:46   ` Peter Xu
2022-09-24  8:47     ` Marc Zyngier
2022-09-24 13:29       ` Peter Xu
2022-09-22 17:01 ` [PATCH 4/6] KVM: Document weakly ordered architecture requirements for dirty ring Marc Zyngier
2022-09-22 17:01 ` [PATCH 5/6] KVM: selftests: dirty-log: Upgrade dirty_gfn_set_collected() to store-release Marc Zyngier
2022-09-22 21:38   ` Paolo Bonzini [this message]
2022-09-23 14:49     ` Marc Zyngier
2022-09-22 17:01 ` [PATCH 6/6] KVM: selftests: dirty-log: Use KVM_CAP_DIRTY_LOG_RING_ORDERED of available Marc Zyngier

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CABgObfbtVAM3t2WC6-8-fLdQZTs6B5Xf2-CZ4oWdJMzXNFWy_g@mail.gmail.com \
    --to=pbonzini@redhat.com \
    --cc=andrew.jones@linux.dev \
    --cc=bgardon@google.com \
    --cc=catalin.marinas@arm.com \
    --cc=dmatlack@google.com \
    --cc=kvm@vger.kernel.org \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=maz@kernel.org \
    --cc=shan.gavin@gmail.com \
    --cc=shuah@kernel.org \
    --cc=will@kernel.org \
    --cc=zhenyzha@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).