From: John David Anglin <dave.anglin@bell.net>
To: Jason Gunthorpe <jgg@nvidia.com>, Leon Romanovsky <leon@kernel.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>,
Leon Romanovsky <leonro@nvidia.com>,
Andreas Larsson <andreas@gaisler.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"David S. Miller" <davem@davemloft.net>,
Geoff Levand <geoff@infradead.org>, Helge Deller <deller@gmx.de>,
Ingo Molnar <mingo@redhat.com>,
iommu@lists.linux.dev,
"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
Jason Wang <jasowang@redhat.com>, Juergen Gross <jgross@suse.com>,
linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Matt Turner <mattst88@gmail.com>,
Michael Ellerman <mpe@ellerman.id.au>,
"Michael S. Tsirkin" <mst@redhat.com>,
Richard Henderson <richard.henderson@linaro.org>,
sparclinux@vger.kernel.org,
Stefano Stabellini <sstabellini@kernel.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Thomas Gleixner <tglx@linutronix.de>,
virtualization@lists.linux.dev, x86@kernel.org,
xen-devel@lists.xenproject.org,
Magnus Lindholm <linmag7@gmail.com>
Subject: Re: [PATCH v1 3/9] parisc: Convert DMA map_page to map_phys interface
Date: Fri, 3 Oct 2025 13:18:32 -0400 [thread overview]
Message-ID: <610b10bc-1aa2-4fad-a40b-be5fcfa04430@bell.net> (raw)
In-Reply-To: <20251003150144.GC3360665@nvidia.com>
On 2025-10-03 11:01 a.m., Jason Gunthorpe wrote:
> This doesn't actually use the virt at all:
>
> offset = ((unsigned long) addr) & ~IOVP_MASK;
> if((size % L1_CACHE_BYTES) || ((unsigned long)addr % L1_CACHE_BYTES))
> ccio_io_pdir_entry(pdir_start, KERNEL_SPACE, (unsigned long)addr, hint);
>
> And ccio_io_pdir_entry():
> pa = lpa(vba);
>
> Is a special instruction that uses virt but AI tells me that special
> LPA instruction is returning phys. Not sure if that is a different
> value than virt_to_phys()..
ccio_io_pdir_entry currently only supports KERNEL_SPACE. For KERNEL_SPACE, lpa() and
virt_to_phys() are equivalent if page is mapped. lpa() returns 0 if a non-access data
TLB fault occurs (i.e., page isn't mapped). Not sure if that matters.
> IDK, I'm not feeling brave enough to drop the LPA but maybe include
> this note in the commit message.
>
--
John David Anglin dave.anglin@bell.net
next prev parent reply other threads:[~2025-10-03 17:21 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-28 15:02 [PATCH v1 0/9] Remove DMA .map_page and .unmap_page callbacks Leon Romanovsky
2025-09-28 15:02 ` [PATCH v1 1/9] alpha: Convert mapping routine to rely on physical address Leon Romanovsky
2025-09-28 17:35 ` Magnus Lindholm
2025-10-03 14:47 ` Jason Gunthorpe
2025-09-28 15:02 ` [PATCH v1 2/9] MIPS/jazzdma: Provide physical address directly Leon Romanovsky
2025-10-03 14:48 ` Jason Gunthorpe
2025-09-28 15:02 ` [PATCH v1 3/9] parisc: Convert DMA map_page to map_phys interface Leon Romanovsky
2025-10-03 15:01 ` Jason Gunthorpe
2025-10-03 17:18 ` John David Anglin [this message]
2025-10-03 17:26 ` Jason Gunthorpe
2025-10-03 20:28 ` John David Anglin
2025-10-05 14:29 ` James Bottomley
2025-10-05 13:22 ` Leon Romanovsky
2025-10-05 23:31 ` Jason Gunthorpe
2025-10-06 4:03 ` Leon Romanovsky
2025-10-05 14:22 ` James Bottomley
2025-09-28 15:02 ` [PATCH v1 4/9] powerpc: Convert to physical address DMA mapping Leon Romanovsky
2025-10-03 16:35 ` Jason Gunthorpe
2025-10-04 6:19 ` Christophe Leroy
2025-10-04 20:02 ` Jason Gunthorpe
2025-09-28 15:02 ` [PATCH v1 5/9] sparc64: Use " Leon Romanovsky
2025-10-03 15:16 ` Jason Gunthorpe
2025-09-28 15:02 ` [PATCH v1 6/9] x86: Use physical address for " Leon Romanovsky
2025-10-03 15:16 ` Jason Gunthorpe
2025-09-28 15:02 ` [PATCH v1 7/9] vdpa: Convert to physical address " Leon Romanovsky
2025-10-03 15:58 ` Jason Gunthorpe
2025-09-28 15:02 ` [PATCH v1 8/9] xen: swiotlb: Convert mapping routine to rely on physical address Leon Romanovsky
2025-10-03 16:18 ` Jason Gunthorpe
2025-09-28 15:02 ` [PATCH v1 9/9] dma-mapping: remove unused map_page callback Leon Romanovsky
2025-09-28 15:17 ` Sam Ravnborg
2025-09-28 15:20 ` Sam Ravnborg
2025-09-28 15:31 ` Leon Romanovsky
2025-09-28 15:28 ` Leon Romanovsky
2025-10-03 16:18 ` Jason Gunthorpe
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