RE: [PATCH v8 03/11] ACPI/IORT: Add helper functions to parse RMR nodes

[Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>]

Hi Eric,

> -----Original Message-----
> From: Eric Auger [mailto:eric.auger@redhat.com]
> Sent: 10 March 2022 10:32
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>;
> linux-arm-kernel@lists.infradead.org; linux-acpi@vger.kernel.org;
> iommu@lists.linux-foundation.org
> Cc: Linuxarm <linuxarm@huawei.com>; lorenzo.pieralisi@arm.com;
> joro@8bytes.org; robin.murphy@arm.com; will@kernel.org; wanghuiqiang
> <wanghuiqiang@huawei.com>; Guohanjun (Hanjun Guo)
> <guohanjun@huawei.com>; steven.price@arm.com; Sami.Mujawar@arm.com;
> jon@solid-run.com; yangyicong <yangyicong@huawei.com>
> Subject: Re: [PATCH v8 03/11] ACPI/IORT: Add helper functions to parse RMR
> nodes
> 
> Hi Shameer,
> 
> On 2/21/22 4:43 PM, Shameer Kolothum wrote:
> > The helper functions here parse through the IORT RMR nodes and
> > populate a reserved region list  corresponding to a given iommu
> > and device(optional). These also go through the ID mappings of
> > the RMR node and retrieves all the SIDs associated with a RMR
> > descriptor.
> >
> > Signed-off-by: Shameer Kolothum
> <shameerali.kolothum.thodi@huawei.com>
> > ---
> >  drivers/acpi/arm64/iort.c | 225
> ++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 225 insertions(+)
> >
> > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> > index 0730c4dbb700..05da9ebff50a 100644
> > --- a/drivers/acpi/arm64/iort.c
> > +++ b/drivers/acpi/arm64/iort.c
> > @@ -830,6 +830,231 @@ static struct acpi_iort_node
> *iort_get_msi_resv_iommu(struct device *dev)
> >  	return NULL;
> >  }
> >
[...]

> > +static void iort_find_rmrs(struct acpi_iort_node *iommu, struct device *dev,
> > +			   struct list_head *head)
> > +{
> > +	struct acpi_table_iort *iort;
> > +	struct acpi_iort_node *iort_node, *iort_end;
> > +	int i;
> > +
> > +	if (iort_table->revision < 5)
> This means E.b and E.c revs are not supported. Is it what we want?

Yes. E.b lacks memory attributes info associated with RMR node. Though E.c 
added those, it broke backward compatibility with ACPICA E.b support and
is now deprecated.

Thanks,
Shameer