On 2019-09-25 15:41, Marc Zyngier wrote:
On 25/09/2019 14:04, Zenghui Yu wrote:
Hi Marc,
Some questions about this patch, mostly to confirm that I would
understand things here correctly.
On 2019/9/24 2:25, Marc Zyngier wrote:
GICv4.1 defines a new VPE table that is potentially shared between
both the ITSs and the redistributors, following complicated
affinity
rules.
To make things more confusing, the programming of this table at
the redistributor level is reusing the GICv4.0 GICR_VPROPBASER
register
for something completely different.
The code flow is somewhat complexified by the need to respect the
affinities required by the HW, meaning that tables can either be
inherited from a previously discovered ITS or redistributor.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
[...]
@@ -1962,6 +1965,65 @@ static bool its_parse_indirect_baser(struct
its_node *its,
return indirect;
}
+static u32 compute_common_aff(u64 val)
+{
+ u32 aff, clpiaff;
+
+ aff = FIELD_GET(GICR_TYPER_AFFINITY, val);
+ clpiaff = FIELD_GET(GICR_TYPER_COMMON_LPI_AFF, val);
+
+ return aff & ~(GENMASK(31, 0) >> (clpiaff * 8));
+}
+
+static u32 compute_its_aff(struct its_node *its)
+{
+ u64 val;
+ u32 svpet;
+
+ /*
+ * Reencode the ITS SVPET and MPIDR as a GICR_TYPER, and compute
+ * the resulting affinity. We then use that to see if this match
+ * our own affinity.
+ */
+ svpet = FIELD_GET(GITS_TYPER_SVPET, its->typer);
+ val = FIELD_PREP(GICR_TYPER_COMMON_LPI_AFF, svpet);
+ val |= FIELD_PREP(GICR_TYPER_AFFINITY, its->mpidr);
+ return compute_common_aff(val);
+}
+
+static struct its_node *find_sibbling_its(struct its_node
*cur_its)
+{
+ struct its_node *its;
+ u32 aff;
+
+ if (!FIELD_GET(GITS_TYPER_SVPET, cur_its->typer))
+ return NULL;
+
+ aff = compute_its_aff(cur_its);
+
+ list_for_each_entry(its, &its_nodes, entry) {
+ u64 baser;
+
+ if (!is_v4_1(its) || its == cur_its)
+ continue;
+
+ if (!FIELD_GET(GITS_TYPER_SVPET, its->typer))
+ continue;
+
+ if (aff != compute_its_aff(its))
+ continue;
+
+ /* GICv4.1 guarantees that the vPE table is GITS_BASER2 */
+ baser = its->tables[2].val;
+ if (!(baser & GITS_BASER_VALID))
+ continue;
+
+ return its;
+ }
+
+ return NULL;
+}
+
static void its_free_tables(struct its_node *its)
{
int i;
@@ -2004,6 +2066,15 @@ static int its_alloc_tables(struct its_node
*its)
break;
case GITS_BASER_TYPE_VCPU:
+ if (is_v4_1(its)) {
+ struct its_node *sibbling;
+
+ if ((sibbling = find_sibbling_its(its))) {
+ its->tables[2] = sibbling->tables[2];
This means thst the vPE table is shared between ITSs which are under
the
same affinity group?
That's indeed what this is trying to do...
Don't we need to set GITS_BASER (by its_setup_baser()) here to tell
this
ITS where the vPE table lacates?
Absolutely. This is a bug. I didn't spot it as my model only has a
single ITS.
FWIW, I've pushed out an updated branch with this fixed as well as the
rest of the comments you had.
Thanks again,
M.
--
Jazz is not dead. It just smells funny...
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