From: Christoph Hellwig <hch@lst.de>
To: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Robin Murphy <robin.murphy@arm.com>,
Ram Pai <linuxram@us.ibm.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org, Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH v3] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory
Date: Wed, 19 Aug 2020 06:43:51 +0200 [thread overview]
Message-ID: <20200819044351.GA19391@lst.de> (raw)
In-Reply-To: <20200818221126.391073-1-bauerman@linux.ibm.com>
On Tue, Aug 18, 2020 at 07:11:26PM -0300, Thiago Jung Bauermann wrote:
> POWER secure guests (i.e., guests which use the Protection Execution
> Facility) need to use SWIOTLB to be able to do I/O with the hypervisor, but
> they don't need the SWIOTLB memory to be in low addresses since the
> hypervisor doesn't have any addressing limitation.
>
> This solves a SWIOTLB initialization problem we are seeing in secure guests
> with 128 GB of RAM: they are configured with 4 GB of crashkernel reserved
> memory, which leaves no space for SWIOTLB in low addresses.
>
> To do this, we use mostly the same code as swiotlb_init(), but allocate the
> buffer using memblock_alloc() instead of memblock_alloc_low().
>
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Looks fine to me (except for the pointlessly long comment lines, but I've
been told that's the powerpc way).
next prev parent reply other threads:[~2020-08-19 4:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-18 22:11 [PATCH v3] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory Thiago Jung Bauermann
2020-08-19 4:43 ` Christoph Hellwig [this message]
2020-08-19 16:50 ` Thiago Jung Bauermann
2020-08-20 2:12 ` Michael Ellerman
2020-08-19 17:00 ` Konrad Rzeszutek Wilk
2020-08-19 19:48 ` Thiago Jung Bauermann
2020-09-17 11:27 ` Michael Ellerman
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