Re: [RFC PATCH 10/33] irqchip/gic-v4-its: Allow use of indirect VCPU tables

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Hi Marc,


On 01/17/2017 04:20 AM, Marc Zyngier wrote:
The VCPU tables can be quite sparse as well, and it makes sense
to use indirect tables as well if possible.
The VCPU table has maximum of 2^16 entries as compared to 2^32 entries in device table. ITS hardware implementations may not support indirect table because of low memory requirement.
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
  drivers/irqchip/irq-gic-v3-its.c | 20 +++++++++++++-------
  1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c
b/drivers/irqchip/irq-gic-v3-its.c
index c92ff4d..14305db1 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1060,10 +1060,13 @@ static int its_setup_baser(struct its_node *its,
struct its_baser *baser,
  	return 0;
  }
-static bool its_parse_baser_device(struct its_node *its, struct its_baser
*baser,
-				   u32 psz, u32 *order)
+static bool its_parse_indirect_baser(struct its_node *its,
+				     struct its_baser *baser,
+				     u32 psz, u32 *order)
  {
-	u64 esz = GITS_BASER_ENTRY_SIZE(its_read_baser(its, baser));
+	u64 tmp = its_read_baser(its, baser);
+	u64 type = GITS_BASER_TYPE(tmp);
+	u64 esz = GITS_BASER_ENTRY_SIZE(tmp);
  	u64 val = GITS_BASER_InnerShareable | GITS_BASER_WaWb;
  	u32 ids = its->device_ids;
  	u32 new_order = *order;
@@ -1102,8 +1105,9 @@ static bool its_parse_baser_device(struct its_node
*its, struct its_baser *baser
  	if (new_order >= MAX_ORDER) {
  		new_order = MAX_ORDER - 1;
  		ids = ilog2(PAGE_ORDER_TO_SIZE(new_order) / (int)esz);
-		pr_warn("ITS@%pa: Device Table too large, reduce ids
%u->%u\n",
-			&its->phys_base, its->device_ids, ids);
+		pr_warn("ITS@%pa: %s Table too large, reduce ids
%u->%u\n",
+			&its->phys_base, its_base_type_string[type],
+			its->device_ids, ids);
  	}
*order = new_order;
@@ -1154,8 +1158,10 @@ static int its_alloc_tables(struct its_node *its)
  		if (type == GITS_BASER_TYPE_NONE)
  			continue;
- if (type == GITS_BASER_TYPE_DEVICE)
-			indirect = its_parse_baser_device(its, baser, psz,
&order);
Try to allocate maximum memory as possible then attempt enabling indirection table.

#define ITS_VPES_MAX            (65536)

if (type == GITS_BASER_TYPE_VCPU)
         order = get_order(esz * ITS_VPES_MAX);

On Qualcomm implementation, 1MBytes, 64536 * 16Byte (vPE entry size) memory is enough to sparse 16bit vPE.
+		if (type == GITS_BASER_TYPE_DEVICE ||
+		    type == GITS_BASER_TYPE_VCPU)
+			indirect = its_parse_indirect_baser(its, baser,
+							    psz, &order);
err = its_setup_baser(its, baser, cache, shr, psz, order,
indirect);
  		if (err < 0) {

--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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