On 15.12.2023 15:18, Roger Pau Monne wrote:
> --- a/xen/drivers/passthrough/x86/iommu.c
> +++ b/xen/drivers/passthrough/x86/iommu.c
> @@ -370,10 +370,88 @@ static unsigned int __hwdom_init hwdom_iommu_map(const
> struct domain *d,
> return perms;
> }
>
> +struct map_data {
> + struct domain *d;
> + unsigned int flush_flags;
> + bool mmio_ro;
> +};
> +
> +static int __hwdom_init cf_check identity_map(unsigned long s, unsigned long
> e,
> + void *data)
> +{
> + struct map_data *info = data;
> + struct domain *d = info->d;
> + long rc;
> +
> + if ( iommu_verbose )
> + printk(XENLOG_INFO " [%010lx, %010lx] R%c\n",
> + s, e, info->mmio_ro ? 'O' : 'W');
> +
> + if ( paging_mode_translate(d) )
> + {
> + if ( info->mmio_ro )
> + {
> + ASSERT_UNREACHABLE();
> + return 0;
Is this meant to be in line with the main return statement's comment?
I'm inclined to ask for an actual error code (-EOPNOTSUPP?) here.
> + }
> + while ( (rc = map_mmio_regions(d, _gfn(s), e - s + 1, _mfn(s))) > 0 )
> + {
> + s += rc;
> + process_pending_softirqs();
> + }
> + }
> + else
> + {
> + const unsigned int perms = IOMMUF_readable | IOMMUF_preempt |
> + (info->mmio_ro ? 0 : IOMMUF_writable);
> +
> + /*
> + * Read-only ranges are only created based on the contents of mmio
> + * read-only rangeset, and hence need the additional iomem
> permissions
> + * check.
> + */
> + while( info->mmio_ro && s <= e && !iomem_access_permitted(d, s, e) )
Nit: Missing blank after "while".
> + {
> + /*
> + * Consume a frame per iteration until the reminder is accessible
Nit: remainder?
> + * or there's nothing left to map.
> + */
> + if ( iomem_access_permitted(d, s, s) )
> + {
> + rc = iommu_map(d, _dfn(s), _mfn(s), 1, perms,
> + &info->flush_flags);
> + if ( rc < 0 )
> + break;
> + /* Must map a frame at least, which is what we request for.
> */
> + ASSERT(rc == 1);
> + process_pending_softirqs();
> + }
> + s++;
> + }
> + while ( (rc = iommu_map(d, _dfn(s), _mfn(s), e - s + 1,
> + perms, &info->flush_flags)) > 0 )
> + {
> + s += rc;
> + process_pending_softirqs();
> + }
> + }
> + ASSERT(rc <= 0);
> + if ( rc )
> + printk(XENLOG_WARNING
> + "IOMMU identity mapping of [%lx, %lx] failed: %ld\n",
> + s, e, rc);
> +
> + /* Ignore errors and attempt to map the remaining regions. */
> + return 0;
> +}
> +
> void __hwdom_init arch_iommu_hwdom_init(struct domain *d)
> {
> unsigned long i, top, max_pfn, start, count;
> unsigned int flush_flags = 0, start_perms = 0;
> + struct rangeset *map;
> + struct map_data map_data = { .d = d };
> + int rc;
>
> BUG_ON(!is_hardware_domain(d));
>
> @@ -397,6 +475,10 @@ void __hwdom_init arch_iommu_hwdom_init(struct domain *d)
> if ( iommu_hwdom_passthrough )
> return;
>
> + map = rangeset_new(NULL, NULL, 0);
> + if ( !map )
> + panic("IOMMU init: unable to allocate rangeset\n");
> +
> max_pfn = (GB(4) >> PAGE_SHIFT) - 1;
> top = max(max_pdx, pfn_to_pdx(max_pfn) + 1);
>
> @@ -451,8 +533,26 @@ void __hwdom_init arch_iommu_hwdom_init(struct domain *d)
> goto commit;
> }
>
> + if ( iommu_verbose )
> + printk(XENLOG_INFO "%pd: identity mappings for IOMMU:\n", d);
> +
> + rc = rangeset_report_ranges(map, 0, ~0UL, identity_map, &map_data);
> + if ( rc )
> + panic("IOMMU unable to create mappings: %d\n", rc);
> + rangeset_destroy(map);
> +
> + if ( is_pv_domain(d) )
> + {
> + map_data.mmio_ro = true;
> + rc = rangeset_report_ranges(mmio_ro_ranges, 0, ~0UL, identity_map,
> + &map_data);
> + if ( rc )
> + panic("IOMMU unable to create read-only mappings: %d\n", rc);
> + }
As it stands identity_map() deliberately returns no error. Yet here
you panic() in case of receiving an error, despite that being impossible?
Also if we want/need to panic() here, can we avoid having two instances
of almost the same string literal in .rodata? Along the lines of
rc = rangeset_report_ranges(map, 0, ~0UL, identity_map, &map_data);
rangeset_destroy(map);
if ( !rc && is_pv_domain(d) )
{
map_data.mmio_ro = true;
rc = rangeset_report_ranges(mmio_ro_ranges, 0, ~0UL, identity_map,
&map_data);
}
if ( rc )
panic("IOMMU unable to create %smappings: %d\n",
map_data.mmio_ro ? "read-only " : "", rc);
?
> + map_data.flush_flags |= flush_flags;
So you decided to still keep the standalone "flush_flags" around. Is
there a particular reason?
Jan
