Date: Fri, 6 May 2022 09:37:36 -0700 From: Kyle Evans <kevans@freebsd.org> To: Ravi Pokala <rpokala@freebsd.org> Cc: Ruslan Bukin <br@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: <CACNAnaEw8wbnvRjEyLC6caOw4=yVEuWceM8JYYGninKyemCaew@mail.gmail.com> In-Reply-To: <450C9313-CB5A-4DCA-97FB-40FC87886F00@panasas.com> References: <202205061551.246FpO6o060060@gitrepo.freebsd.org> <450C9313-CB5A-4DCA-97FB-40FC87886F00@panasas.com>
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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@Fr= eeBSD.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=3D0b6bacc7874f9c68ad35b0= 6f1a7614171eb9ab10 > > 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 =3D OF_getproplen(node, "iommu-map"); > + if (len <=3D 0) > + return (ENOENT); > + if (len > sizeof(map)) > + return (ENOMEM); > + > + len =3D OF_getencprop(node, "iommu-map", map, 16); > + > + err =3D ENOENT; > + mask =3D 0xffffffff; > + OF_getencprop(node, "iommu-map-mask", &mask, sizeof(mask)); > + > + masked_rid =3D pci_rid & mask; > + for (i =3D 0; i < len; i +=3D 4) { > + rid_base =3D map[i + 0]; > + rid_length =3D 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' i= s the loop iterator; doesn't that mean you're accessing outside the array a= fter 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.
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