Date: Fri, 6 May 2022 19:31:47 +0100 From: Ruslan Bukin <br@freebsd.org> To: Kyle Evans <kevans@freebsd.org> Cc: Ravi Pokala <rpokala@freebsd.org>, src-committers <src-committers@freebsd.org>, "<dev-commits-src-all@freebsd.org>" <dev-commits-src-all@freebsd.org>, dev-commits-src-main@freebsd.org Subject: Re: 0b6bacc7874f - main - Add ofw_bus_iommu_map() that maps PCI requester ID to an IOMMU specifier based on "iommu-map" DTS property. Message-ID: <YnVpkxWJndqKtc/i@bsdpad.com> In-Reply-To: <CACNAnaEw8wbnvRjEyLC6caOw4=yVEuWceM8JYYGninKyemCaew@mail.gmail.com> References: <202205061551.246FpO6o060060@gitrepo.freebsd.org> <450C9313-CB5A-4DCA-97FB-40FC87886F00@panasas.com> <CACNAnaEw8wbnvRjEyLC6caOw4=yVEuWceM8JYYGninKyemCaew@mail.gmail.com>
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On Fri, May 06, 2022 at 09:37:36AM -0700, Kyle Evans wrote: > On Fri, May 6, 2022 at 9:25 AM Ravi Pokala <rpokala@freebsd.org> wrote: > > > > -----Original Message----- > > From: <owner-src-committers@freebsd.org> on behalf of Ruslan Bukin <br@FreeBSD.org> > > Date: 2022-05-06, Friday at 08:51 > > To: <src-committers@FreeBSD.org>, <dev-commits-src-all@FreeBSD.org>, <dev-commits-src-main@FreeBSD.org> > > Subject: git: 0b6bacc7874f - main - Add ofw_bus_iommu_map() that maps PCI requester ID to an IOMMU specifier based on "iommu-map" DTS property. > > > > The branch main has been updated by br: > > > > URL: https://cgit.FreeBSD.org/src/commit/?id=0b6bacc7874f9c68ad35b06f1a7614171eb9ab10 > > > > commit 0b6bacc7874f9c68ad35b06f1a7614171eb9ab10 > > Author: Ruslan Bukin <br@FreeBSD.org> > > AuthorDate: 2022-05-06 15:41:11 +0000 > > Commit: Ruslan Bukin <br@FreeBSD.org> > > CommitDate: 2022-05-06 15:48:04 +0000 > > > > Add ofw_bus_iommu_map() that maps PCI requester ID to an IOMMU > > specifier based on "iommu-map" DTS property. > > > > Sponsored by: UKRI > > --- > > sys/dev/ofw/ofw_bus_subr.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ > > sys/dev/ofw/ofw_bus_subr.h | 3 ++- > > 2 files changed, 46 insertions(+), 1 deletion(-) > > > > diff --git a/sys/dev/ofw/ofw_bus_subr.c b/sys/dev/ofw/ofw_bus_subr.c > > index ea57d1086779..408d554b3c7f 100644 > > --- a/sys/dev/ofw/ofw_bus_subr.c > > +++ b/sys/dev/ofw/ofw_bus_subr.c > > @@ -491,6 +491,50 @@ ofw_bus_msimap(phandle_t node, uint16_t pci_rid, phandle_t *msi_parent, > > return (err); > > } > > > > +int > > +ofw_bus_iommu_map(phandle_t node, uint16_t pci_rid, phandle_t *iommu_parent, > > + uint32_t *iommu_rid) > > +{ > > + pcell_t mask, iommu_base, rid_base, rid_length; > > + uint32_t masked_rid; > > + pcell_t map[4]; > > + ssize_t len; > > + int err, i; > > + > > + len = OF_getproplen(node, "iommu-map"); > > + if (len <= 0) > > + return (ENOENT); > > + if (len > sizeof(map)) > > + return (ENOMEM); > > + > > + len = OF_getencprop(node, "iommu-map", map, 16); > > + > > + err = ENOENT; > > + mask = 0xffffffff; > > + OF_getencprop(node, "iommu-map-mask", &mask, sizeof(mask)); > > + > > + masked_rid = pci_rid & mask; > > + for (i = 0; i < len; i += 4) { > > + rid_base = map[i + 0]; > > + rid_length = map[i + 3]; > > > > Hi Ruslan, > > > > I'm confused by this. 'map' is declared as a 4-element array, which means 'map[i + 0]' and 'map[i + 3]' are both only valid when 'i' is 0. But 'i' is the loop iterator; doesn't that mean you're accessing outside the array after the 0th time through the loop? > > > > The comparison looks like it's wrong and inherited from > ofw_bus_msimap() -- i is in terms of # cells, OF_getencprop returns > size in bytes, This version only holds one mapping (four cells) at a > time, so the intention is just one iteration through the loop. > > We'll need to extend this at some point, the M1 FDT has 3 4-cell mappings > here. ofw_bus_msimap() was almost an exact fit, and an adapted version > is what I use in my m1 branch. iommu-map property is an arbitrary number of tuples of (rid-base,iommu,iommu-base,length). Do you mean that some of the items in the tuple could occupy more than one 32-bit cell? I grepped DTS tree, so far each of occurrence takes just 1 cell. Ruslan
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