From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>,
Yan Zhao <yan.y.zhao@intel.com>
Cc: "Philippe Mathieu-Daudé" <philmd@redhat.com>,
"Alex Williamson" <alex.williamson@redhat.com>,
xin.zeng@intel.com, "QEMU Developers" <qemu-devel@nongnu.org>
Subject: Re: [PATCH v6 1/3] memory: drop guest writes to read-only ram device regions
Date: Thu, 21 May 2020 16:38:47 +0200 [thread overview]
Message-ID: <9dd7f00b-1199-1097-80d4-1b700c0f28d6@redhat.com> (raw)
In-Reply-To: <CAFEAcA-8NH_4ZV0J9urBZdQWmqOe-Nyy4y2gLAjTJ08MpfFY0g@mail.gmail.com>
On 30/04/20 11:40, Peter Maydell wrote:
>> This does not "drop" a write to a r/o region -- it causes it to generate
>> whatever the guest architecture's equivalent of a bus error is (eg data
>> abort on Arm).
> More generally, this change seems a bit odd: currently we do not
> check the mr->readonly flag here, but in general guests don't get
> to write to ROM areas. Where is that check currently done
Writes to ROM are directed to mr->ops unassigned_mem_ops. Because _all_
ram-device reads and writes go through the ops, for ram-device we have
to stick the check for mr->readonly in the ops.
On one hand, I was quite surprised to see that unassigned_mem_write does
not return MEMTX_ERROR now that I looked at it.
On the other hand, we should use MEMTX_ERROR in patch 2 as well, if we
decide it's the way to go.
(Sorry Yan for the late response).
Paolo
next prev parent reply other threads:[~2020-05-21 14:39 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 8:07 [PATCH v6 0/3] drop writes to read-only ram device & vfio regions Yan Zhao
2020-04-30 8:09 ` [PATCH v6 1/3] memory: drop guest writes to read-only ram device regions Yan Zhao
2020-04-30 9:40 ` Peter Maydell
2020-04-30 10:11 ` Yan Zhao
2020-05-21 14:38 ` Paolo Bonzini [this message]
2020-05-25 1:18 ` Yan Zhao
2020-05-25 10:20 ` Paolo Bonzini
2020-05-25 10:54 ` Philippe Mathieu-Daudé
2020-05-25 11:04 ` Paolo Bonzini
2020-05-26 2:11 ` Yan Zhao
2020-05-26 9:14 ` Peter Maydell
2020-05-26 9:26 ` Peter Maydell
2020-05-28 4:35 ` Yan Zhao
2020-05-28 5:10 ` Paolo Bonzini
2020-05-28 6:15 ` Yan Zhao
2020-04-30 8:13 ` [PATCH v6 2/3] hw/vfio: drop guest writes to ro regions Yan Zhao
2020-04-30 8:13 ` [PATCH v6 3/3] hw/vfio: let read-only flag take effect for mmap'd regions Yan Zhao
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