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[86.176.94.160]) by smtp.gmail.com with ESMTPSA id j26sm1095600wrc.79.2020.09.16.02.07.38 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 16 Sep 2020 02:07:39 -0700 (PDT) From: Paul Durrant X-Google-Original-From: "Paul Durrant" To: "'Jan Beulich'" , "'Oleksandr Tyshchenko'" Cc: , "'Oleksandr Tyshchenko'" , "'Julien Grall'" , "'Stefano Stabellini'" , "'Julien Grall'" References: <1599769330-17656-1-git-send-email-olekstysh@gmail.com> <1599769330-17656-15-git-send-email-olekstysh@gmail.com> <44b19ee1-dc34-3a46-0b4b-7196faadcb5c@suse.com> In-Reply-To: <44b19ee1-dc34-3a46-0b4b-7196faadcb5c@suse.com> Subject: RE: [PATCH V1 14/16] xen/ioreq: Use guest_cmpxchg64() instead of cmpxchg() Date: Wed, 16 Sep 2020 10:07:38 +0100 Message-ID: <002a01d68c08$d3895c70$7a9c1550$@xen.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 16.0 Content-Language: en-gb Thread-Index: AQIQ4beZ3sUmYihKXwfoVgy4BRIJGwM3mpe2Aj4RmJGoyqB/QA== X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Reply-To: paul@xen.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" > -----Original Message----- > From: Jan Beulich > Sent: 16 September 2020 10:04 > To: Oleksandr Tyshchenko > Cc: xen-devel@lists.xenproject.org; Oleksandr Tyshchenko ; Paul Durrant > ; Julien Grall ; Stefano Stabellini ; Julien > Grall > Subject: Re: [PATCH V1 14/16] xen/ioreq: Use guest_cmpxchg64() instead of cmpxchg() > > On 10.09.2020 22:22, Oleksandr Tyshchenko wrote: > > @@ -1325,7 +1327,7 @@ static int hvm_send_buffered_ioreq(struct hvm_ioreq_server *s, ioreq_t *p) > > > > new.read_pointer = old.read_pointer - n * IOREQ_BUFFER_SLOT_NUM; > > new.write_pointer = old.write_pointer - n * IOREQ_BUFFER_SLOT_NUM; > > - cmpxchg(&pg->ptrs.full, old.full, new.full); > > + guest_cmpxchg64(d, &pg->ptrs.full, old.full, new.full); > > But the memory we're updating is shared with s->emulator, not with d, > if I'm not mistaken. > You're not mistaken. Paul > Jan