From: Andrew Cooper <Andrew.Cooper3@citrix.com>
To: Christoph Hellwig <hch@lst.de>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>
Cc: "x86@kernel.org" <x86@kernel.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>, Joerg Roedel <joro@8bytes.org>,
"David Woodhouse" <dwmw2@infradead.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
"Robin Murphy" <robin.murphy@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"linux-ia64@vger.kernel.org" <linux-ia64@vger.kernel.org>,
"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"tboot-devel@lists.sourceforge.net"
<tboot-devel@lists.sourceforge.net>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Subject: Re: [PATCH 08/12] x86: centralize setting SWIOTLB_FORCE when guest memory encryption is enabled
Date: Tue, 1 Mar 2022 11:39:29 +0000 [thread overview]
Message-ID: <8e623a11-d809-4fab-401c-2ce609a9fc14@citrix.com> (raw)
In-Reply-To: <20220301105311.885699-9-hch@lst.de>
On 01/03/2022 10:53, Christoph Hellwig wrote:
> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index 2ac0ef9c2fb76..7ab7002758396 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -53,6 +53,13 @@ static void __init pci_swiotlb_detect(void)
> if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
> x86_swiotlb_enable = true;
>
> + /*
> + * Guest with guest memory encryption must always do I/O through a
> + * bounce buffer as the hypervisor can't access arbitrary VM memory.
This isn't really "must". The guest is perfectly capable of sharing
memory with the hypervisor.
It's just that for now, bounce buffering is allegedly faster, and the
simple way of getting it working.
~Andrew
next prev parent reply other threads:[~2022-03-01 11:40 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-01 10:52 cleanup swiotlb initialization v4 Christoph Hellwig
2022-03-01 10:53 ` [PATCH 01/12] dma-direct: use is_swiotlb_active in dma_direct_map_page Christoph Hellwig
2022-03-01 10:53 ` [PATCH 02/12] swiotlb: make swiotlb_exit a no-op if SWIOTLB_FORCE is set Christoph Hellwig
2022-03-01 10:53 ` [PATCH 03/12] swiotlb: simplify swiotlb_max_segment Christoph Hellwig
2022-03-01 10:53 ` [PATCH 04/12] swiotlb: rename swiotlb_late_init_with_default_size Christoph Hellwig
2022-03-01 10:53 ` [PATCH 05/12] swiotlb: pass a gfp_mask argument to swiotlb_init_late Christoph Hellwig
2022-03-01 10:53 ` [PATCH 06/12] MIPS/octeon: use swiotlb_init instead of open coding it Christoph Hellwig
2022-03-03 16:39 ` Thomas Bogendoerfer
2022-03-01 10:53 ` [PATCH 07/12] x86: remove the IOMMU table infrastructure Christoph Hellwig
2022-03-01 10:53 ` [PATCH 08/12] x86: centralize setting SWIOTLB_FORCE when guest memory encryption is enabled Christoph Hellwig
2022-03-01 11:39 ` Andrew Cooper [this message]
2022-03-01 11:43 ` Christoph Hellwig
2022-03-01 10:53 ` [PATCH 09/12] swiotlb: make the swiotlb_init interface more useful Christoph Hellwig
2022-03-01 10:53 ` [PATCH 10/12] swiotlb: add a SWIOTLB_ANY flag to lift the low memory restriction Christoph Hellwig
2022-03-04 18:12 ` Michael Kelley (LINUX)
2022-03-04 18:27 ` Dongli Zhang
2022-03-06 17:01 ` Michael Kelley (LINUX)
2022-03-01 10:53 ` [PATCH 11/12] swiotlb: merge swiotlb-xen initialization into swiotlb Christoph Hellwig
2022-03-02 2:55 ` Stefano Stabellini
2022-03-02 8:15 ` Christoph Hellwig
2022-03-03 1:25 ` Stefano Stabellini
2022-03-03 10:59 ` Christoph Hellwig
2022-03-03 22:49 ` Stefano Stabellini
2022-03-04 16:34 ` Christoph Hellwig
2022-03-04 23:22 ` Stefano Stabellini
2022-03-02 13:15 ` Boris Ostrovsky
2022-03-02 13:17 ` Boris Ostrovsky
2022-03-03 10:57 ` Christoph Hellwig
2022-03-03 19:06 ` Boris Ostrovsky
2022-03-04 17:28 ` Christoph Hellwig
2022-03-04 17:36 ` Boris Ostrovsky
2022-03-04 17:43 ` Christoph Hellwig
2022-03-04 20:18 ` Boris Ostrovsky
2022-03-04 21:03 ` Christoph Hellwig
2022-03-08 21:38 ` Boris Ostrovsky
2022-03-09 6:18 ` Christoph Hellwig
2022-03-09 15:18 ` Boris Ostrovsky
2022-03-01 10:53 ` [PATCH 12/12] x86: remove cruft from <asm/dma-mapping.h> Christoph Hellwig
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=8e623a11-d809-4fab-401c-2ce609a9fc14@citrix.com \
--to=andrew.cooper3@citrix.com \
--cc=anshuman.khandual@arm.com \
--cc=baolu.lu@linux.intel.com \
--cc=boris.ostrovsky@oracle.com \
--cc=dwmw2@infradead.org \
--cc=hch@lst.de \
--cc=iommu@lists.linux-foundation.org \
--cc=jgross@suse.com \
--cc=joro@8bytes.org \
--cc=konrad.wilk@oracle.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-ia64@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux-s390@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=robin.murphy@arm.com \
--cc=sstabellini@kernel.org \
--cc=tboot-devel@lists.sourceforge.net \
--cc=thomas.lendacky@amd.com \
--cc=x86@kernel.org \
--cc=xen-devel@lists.xenproject.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).