From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
linuxppc-dev@lists.ozlabs.org, Ram Pai <linuxram@us.ibm.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v3] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory
Date: Wed, 19 Aug 2020 13:50:31 -0300 [thread overview]
Message-ID: <87lfiaeg14.fsf@morokweng.localdomain> (raw)
In-Reply-To: <20200819044351.GA19391@lst.de>
Christoph Hellwig <hch@lst.de> writes:
> 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).
Thanks! Do I have your Reviewed-by?
--
Thiago Jung Bauermann
IBM Linux Technology Center
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next prev parent reply other threads:[~2020-08-19 16:50 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
2020-08-19 16:50 ` Thiago Jung Bauermann [this message]
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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