[RFC PATCH mpam mpam/snapshot/v6.11-rc1 1/6] arm_mpam: Set INTERNAL as needed when setting MSC controls

[Zeng Heng]

From: Dave Martin <Dave.Martin at arm.com>

Currently, when an MSC implements PARTID narrowing, MPAMCFG_PART_SEL is
left set to the reqPARTID while while programming resource controls in
an MSC.

The MPAM architecture does not guarantee that any particular resource
controls will be updated correctly in this scenario.  Instead,
MPAMCFG_PART_SEL must be written with the corresponding intPARTID and
with the INTERNAL bit set before attempting to program resource controls.
Only the PARTID->intPARTID mappings can be written without the INTERNAL
bit set in MPAMCFG_PART_SEL.

Fix it, by rewriting MPAMCFG_PART_SEL appropriately after setting the
intPARTID mapping.

The MPAMCFG_INTPARTID_INTERNAL flag is not currently accepted as
input to the __mpam_part_sel() helper.  In the interest of keeping
the code clean, break this helper up.

Signed-off-by: Dave Martin <Dave.Martin at arm.com>
Signed-off-by: James Morse <james.morse at arm.com>
---
 drivers/platform/arm64/mpam/mpam_devices.c | 26 +++++++++++++++++-----
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/platform/arm64/mpam/mpam_devices.c b/drivers/platform/arm64/mpam/mpam_devices.c
index 954b0017eda8..e7ab1bfbf831 100644
--- a/drivers/platform/arm64/mpam/mpam_devices.c
+++ b/drivers/platform/arm64/mpam/mpam_devices.c
@@ -204,15 +204,27 @@ static u64 mpam_msc_read_esr(struct mpam_msc *msc)
 	return (esr_high << 32) | esr_low;
 }
 
+static void __mpam_part_sel_raw(u32 partsel, struct mpam_msc *msc)
+{
+	lockdep_assert_held(&msc->part_sel_lock);
+	mpam_write_partsel_reg(msc, PART_SEL, partsel);
+}
+
 static void __mpam_part_sel(u8 ris_idx, u16 partid, struct mpam_msc *msc)
 {
-	u32 partsel;
+	u32 partsel = FIELD_PREP(MPAMCFG_PART_SEL_RIS, ris_idx) |
+		      FIELD_PREP(MPAMCFG_PART_SEL_PARTID_SEL, partid);
 
-	lockdep_assert_held(&msc->part_sel_lock);
+	__mpam_part_sel_raw(partsel, msc);
+}
 
-	partsel = FIELD_PREP(MPAMCFG_PART_SEL_RIS, ris_idx) |
-		  FIELD_PREP(MPAMCFG_PART_SEL_PARTID_SEL, partid);
-	mpam_write_partsel_reg(msc, PART_SEL, partsel);
+static void __mpam_intpart_sel(u8 ris_idx, u16 intpartid, struct mpam_msc *msc)
+{
+	u32 partsel = FIELD_PREP(MPAMCFG_PART_SEL_RIS, ris_idx) |
+		      FIELD_PREP(MPAMCFG_PART_SEL_PARTID_SEL, intpartid) |
+		      MPAMCFG_PART_SEL_INTERNAL;
+
+	__mpam_part_sel_raw(partsel, msc);
 }
 
 int mpam_register_requestor(u16 partid_max, u8 pmg_max)
@@ -1529,9 +1541,11 @@ static void mpam_reprogram_ris_partid(struct mpam_msc_ris *ris, u16 partid,
 	mutex_lock(&msc->part_sel_lock);
 	__mpam_part_sel(ris->ris_idx, partid, msc);
 
-	if (mpam_has_feature(mpam_feat_partid_nrw, rprops))
+	if (mpam_has_feature(mpam_feat_partid_nrw, rprops)) {
 		mpam_write_partsel_reg(msc, INTPARTID,
 				       MPAMCFG_INTPARTID_INTERNAL | partid);
+		__mpam_intpart_sel(ris->ris_idx, partid, msc);
+	}
 
 	if (mpam_has_feature(mpam_feat_cpor_part, rprops)) {
 		if (mpam_has_feature(mpam_feat_cpor_part, cfg))
-- 
2.25.1