From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [Qemu-devel] [PATCH] Add a memory barrier to guest memory access function
Date: Tue, 22 May 2012 10:00:11 +1000 [thread overview]
Message-ID: <1337644811.2779.131.camel@pasglop> (raw)
In-Reply-To: <20120521222243.GI17031@redhat.com>
On Tue, 2012-05-22 at 01:22 +0300, Michael S. Tsirkin wrote:
> > Again, from which originator ? From a given initiator, nothing
> bypasses
> > anything, so the right thing to do here is a full mb(). However, I
> > suspect what you are talking about here is read -responses- not
> > bypassing writes in the direction of the response (ie, the
> "flushing"
> > semantic of reads) which is a different matter.
>
> No. My spec says:
> A3, A4
> A Posted Request must be able to pass Non-Posted Requests to avoid
> deadlocks.
An additional note about that one: It only applies obviously if the
initiator doesn't wait for the read response before shooting the write.
Most devices actually do wait. Here too, we would have to explicitly
make sure if what is the right semantic on an individual device basis.
Ben.
next prev parent reply other threads:[~2012-05-22 0:00 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-10 4:48 [Qemu-devel] [PATCH 00/13] IOMMU infrastructure Benjamin Herrenschmidt
2012-05-10 4:48 ` [Qemu-devel] [PATCH 01/13] Better support for dma_addr_t variables Benjamin Herrenschmidt
2012-05-10 4:48 ` [Qemu-devel] [PATCH 02/13] Implement cpu_physical_memory_zero() Benjamin Herrenschmidt
2012-05-15 0:42 ` Anthony Liguori
2012-05-15 1:23 ` David Gibson
2012-05-15 2:03 ` Anthony Liguori
2012-05-10 4:48 ` [Qemu-devel] [PATCH 03/13] iommu: Add universal DMA helper functions Benjamin Herrenschmidt
2012-05-10 4:48 ` [Qemu-devel] [PATCH 04/13] usb-ohci: Use " Benjamin Herrenschmidt
2012-05-10 4:48 ` [Qemu-devel] [PATCH 05/13] iommu: Make sglists and dma_bdrv helpers use new universal DMA helpers Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 06/13] ide/ahci: Use universal DMA helper functions Benjamin Herrenschmidt
2012-05-21 1:51 ` [Qemu-devel] [PATCH 06/13 - UPDATED] " Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 07/13] usb: Convert usb_packet_{map, unmap} to universal DMA helpers Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 08/13] iommu: Introduce IOMMU emulation infrastructure Benjamin Herrenschmidt
2012-05-15 0:49 ` Anthony Liguori
2012-05-15 1:42 ` David Gibson
2012-05-15 2:03 ` Anthony Liguori
2012-05-15 2:32 ` Benjamin Herrenschmidt
2012-05-15 2:50 ` Anthony Liguori
2012-05-15 3:02 ` Benjamin Herrenschmidt
2012-05-15 14:02 ` Anthony Liguori
2012-05-15 21:55 ` Benjamin Herrenschmidt
2012-05-15 22:02 ` Anthony Liguori
2012-05-15 23:08 ` Benjamin Herrenschmidt
2012-05-15 23:58 ` Anthony Liguori
2012-05-16 0:41 ` Benjamin Herrenschmidt
2012-05-16 0:54 ` Anthony Liguori
2012-05-16 1:20 ` Benjamin Herrenschmidt
2012-05-16 19:36 ` Anthony Liguori
2012-05-10 4:49 ` [Qemu-devel] [PATCH 09/13] iommu: Add facility to cancel in-use dma memory maps Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 10/13] pseries: Convert sPAPR TCEs to use generic IOMMU infrastructure Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 11/13] iommu: Allow PCI to use " Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 12/13] pseries: Implement IOMMU and DMA for PAPR PCI devices Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function Benjamin Herrenschmidt
2012-05-15 0:52 ` Anthony Liguori
2012-05-15 1:11 ` Benjamin Herrenschmidt
2012-05-15 1:44 ` David Gibson
2012-05-16 4:35 ` Benjamin Herrenschmidt
2012-05-16 5:51 ` David Gibson
2012-05-16 19:39 ` Anthony Liguori
2012-05-16 21:10 ` Benjamin Herrenschmidt
2012-05-16 21:12 ` Benjamin Herrenschmidt
2012-05-17 0:07 ` Benjamin Herrenschmidt
2012-05-17 0:24 ` Benjamin Herrenschmidt
2012-05-17 0:52 ` [Qemu-devel] [RFC/PATCH] Add a memory barrier to guest memory access functions Benjamin Herrenschmidt
2012-05-17 2:28 ` Anthony Liguori
2012-05-17 2:44 ` Benjamin Herrenschmidt
2012-05-17 22:09 ` Anthony Liguori
2012-05-18 1:04 ` David Gibson
2012-05-18 1:16 ` Benjamin Herrenschmidt
2012-05-17 3:35 ` David Gibson
2012-05-18 6:53 ` [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function Paolo Bonzini
2012-05-18 8:18 ` Benjamin Herrenschmidt
2012-05-18 8:57 ` Paolo Bonzini
2012-05-18 22:26 ` Benjamin Herrenschmidt
2012-05-19 7:24 ` Paolo Bonzini
2012-05-20 21:36 ` Benjamin Herrenschmidt
2012-05-21 1:56 ` [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions Benjamin Herrenschmidt
2012-05-21 8:11 ` Paolo Bonzini
2012-05-21 8:31 ` Michael S. Tsirkin
2012-05-21 8:58 ` Benjamin Herrenschmidt
2012-05-21 9:07 ` Benjamin Herrenschmidt
2012-05-21 9:16 ` Benjamin Herrenschmidt
2012-05-21 9:34 ` Michael S. Tsirkin
2012-05-21 9:53 ` Benjamin Herrenschmidt
2012-05-21 10:31 ` Michael S. Tsirkin
2012-05-21 11:45 ` Benjamin Herrenschmidt
2012-05-21 12:18 ` Michael S. Tsirkin
2012-05-21 15:16 ` Paolo Bonzini
2012-05-21 21:58 ` [Qemu-devel] [PATCH] Add a memory barrier to guest memory access function Benjamin Herrenschmidt
2012-05-21 22:22 ` Michael S. Tsirkin
2012-05-21 22:56 ` Benjamin Herrenschmidt
2012-05-22 5:11 ` Michael S. Tsirkin
2012-05-22 0:00 ` Benjamin Herrenschmidt [this message]
2012-05-22 4:19 ` Rusty Russell
2012-05-21 22:18 ` [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions Anthony Liguori
2012-05-21 22:26 ` Benjamin Herrenschmidt
2012-05-21 22:31 ` Anthony Liguori
2012-05-21 22:44 ` Michael S. Tsirkin
2012-05-21 23:02 ` Benjamin Herrenschmidt
2012-05-22 4:34 ` [Qemu-devel] [PATCH] Add a memory barrier to DMA functions Benjamin Herrenschmidt
2012-05-22 4:51 ` Benjamin Herrenschmidt
2012-05-22 7:17 ` Benjamin Herrenschmidt
2012-05-22 11:14 ` Michael S. Tsirkin
2012-05-22 11:41 ` Benjamin Herrenschmidt
2012-05-22 12:03 ` Michael S. Tsirkin
2012-05-22 21:24 ` Benjamin Herrenschmidt
2012-05-22 21:40 ` Anthony Liguori
2012-05-21 22:37 ` [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions Michael S. Tsirkin
2012-05-15 0:52 ` [Qemu-devel] [PATCH 00/13] IOMMU infrastructure Anthony Liguori
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=1337644811.2779.131.camel@pasglop \
--to=benh@kernel.crashing.org \
--cc=anthony@codemonkey.ws \
--cc=david@gibson.dropbear.id.au \
--cc=mst@redhat.com \
--cc=pbonzini@redhat.com \
--cc=qemu-devel@nongnu.org \
/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).