Hi Stefano,
On 01/06/2022 00:13, Stefano Stabellini wrote:
arm: Set p2m_type to p2m_mmio_direct_nc_x for reserved memory
regions
This is the enhancement of the 46b3dd3718144ca6ac2c12a3b106e57fb7156554.
Those patch introduces p2m_mmio_direct_nc_x p2m type which sets the
e->p2m.xn = 0 for the reserved-memory, such as vpu encoder/decoder.
Set p2m_mmio_direct_nc_x in map_regions_p2mt for reserved-memory the
same way it does in map_mmio_regions. This change is for the case
when vpu encoder/decoder works in DomO and not passed-through to the
Guest Domains.
Signed-off-by: Oleksii Moisieiev <oleksii_moisie...@epam.com>
---
xen/arch/arm/p2m.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index e9568dab88..bb1f681b71 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -1333,6 +1333,13 @@ int map_regions_p2mt(struct domain *d,
mfn_t mfn,
p2m_type_t p2mt)
{
+ if (((long)gfn_x(gfn) >= (GUEST_RAM0_BASE >> PAGE_SHIFT)) &&
+ (((long)gfn_x(gfn) + nr) <=
+ ((GUEST_RAM0_BASE + GUEST_RAM0_SIZE)>> PAGE_SHIFT)))
I am afraid I don't understand what this check is for. In a normal setup, we
don't know where the reserved regions are mapped. Only the caller may know
that.
For dom0, this decision could be taken in map_range_to_domain(). For the domU,
we would need to let the toolstack to chose the memory attribute.
I think the intent of the check is to recognize that map_regions_p2mt
was called for a normal memory location and, if so, change the p2m type
to p2m_mmio_direct_nc_x.
That would have made sense if it was for a domU. But AFAICT the intent
is to address the problem for dom0.
Technically, GUEST_RAM0_BASE describes the RAM for the guest and not
dom0. Maybe they are the same on his HW, but without more details I
can't confirm that. And therefore...
As a downstream, the patch below is one of the easiest way to have a
self-contained change to fix the problem described above.
... there are no way for me to tell whether this patch would still be
fine for a downstream project.
Cheers,
[...]
--
Julien Grall
