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From: Robin Murphy <robin.murphy@arm.com>
To: will@kernel.org, joro@8bytes.org
Cc: robh@kernel.org, tomeu.vizoso@collabora.com,
	narmstrong@baylibre.com, steven.price@arm.com,
	iommu@lists.linux-foundation.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/3] iommu/io-pgtable-arm: Correct Mali attributes
Date: Wed, 11 Sep 2019 15:42:07 +0100
Message-ID: <8b9515e86053910196cbc90b71af97be8928585c.1568211045.git.robin.murphy@arm.com> (raw)
In-Reply-To: <cover.1568211045.git.robin.murphy@arm.com>

Whilst Midgard's MEMATTR follows a similar principle to the VMSA MAIR,
the actual attribute values differ, so although it currently appears to
work to some degree, we probably shouldn't be using our standard stage 1
MAIR for that. Instead, generate a reasonable MEMATTR with attribute
values borrowed from the kbase driver; at this point we'll be overriding
or ignoring pretty much all of the LPAE config, so just implement these
Mali details in a dedicated allocator instead of pretending to subclass
the standard VMSA format.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/iommu/io-pgtable-arm.c | 53 +++++++++++++++++++++++++---------
 1 file changed, 40 insertions(+), 13 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 161a7d56264d..9e35cd991f06 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -167,6 +167,9 @@
 #define ARM_MALI_LPAE_TTBR_READ_INNER	BIT(2)
 #define ARM_MALI_LPAE_TTBR_SHARE_OUTER	BIT(4)
 
+#define ARM_MALI_LPAE_MEMATTR_IMP_DEF	0x88ULL
+#define ARM_MALI_LPAE_MEMATTR_WRITE_ALLOC 0x8DULL
+
 /* IOPTE accessors */
 #define iopte_deref(pte,d) __va(iopte_to_paddr(pte, d))
 
@@ -1013,27 +1016,51 @@ arm_32_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
 static struct io_pgtable *
 arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
 {
-	struct io_pgtable *iop;
+	struct arm_lpae_io_pgtable *data;
+
+	/* No quirks for Mali (hopefully) */
+	if (cfg->quirks)
+		return NULL;
 
 	if (cfg->ias != 48 || cfg->oas > 40)
 		return NULL;
 
 	cfg->pgsize_bitmap &= (SZ_4K | SZ_2M | SZ_1G);
-	iop = arm_64_lpae_alloc_pgtable_s1(cfg, cookie);
-	if (iop) {
-		u64 mair, ttbr;
 
-		/* Copy values as union fields overlap */
-		mair = cfg->arm_lpae_s1_cfg.mair[0];
-		ttbr = cfg->arm_lpae_s1_cfg.ttbr[0];
+	data = arm_lpae_alloc_pgtable(cfg);
+	if (!data)
+		return NULL;
 
-		cfg->arm_mali_lpae_cfg.memattr = mair;
-		cfg->arm_mali_lpae_cfg.transtab = ttbr |
-			ARM_MALI_LPAE_TTBR_READ_INNER |
-			ARM_MALI_LPAE_TTBR_ADRMODE_TABLE;
-	}
+	/*
+	 * MEMATTR: Mali has no actual notion of a non-cacheable type, so the
+	 * best we can do is mimic the out-of-tree driver and hope that the
+	 * "implementation-defined caching policy" is good enough. Similarly,
+	 * we'll use it for the sake of a valid attribute for our 'device'
+	 * index, although callers should never request that in practice.
+	 */
+	cfg->arm_mali_lpae_cfg.memattr =
+		(ARM_MALI_LPAE_MEMATTR_IMP_DEF
+		 << ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_NC)) |
+		(ARM_MALI_LPAE_MEMATTR_WRITE_ALLOC
+		 << ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_CACHE)) |
+		(ARM_MALI_LPAE_MEMATTR_IMP_DEF
+		 << ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_DEV));
 
-	return iop;
+	data->pgd = __arm_lpae_alloc_pages(data->pgd_size, GFP_KERNEL, cfg);
+	if (!data->pgd)
+		goto out_free_data;
+
+	/* Ensure the empty pgd is visible before TRANSTAB can be written */
+	wmb();
+
+	cfg->arm_mali_lpae_cfg.transtab = virt_to_phys(data->pgd) |
+					  ARM_MALI_LPAE_TTBR_READ_INNER |
+					  ARM_MALI_LPAE_TTBR_ADRMODE_TABLE;
+	return &data->iop;
+
+out_free_data:
+	kfree(data);
+	return NULL;
 }
 
 struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns = {
-- 
2.21.0.dirty

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Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-11 14:42 [PATCH 0/3] iommu/io-pgtable-arm: Mali LPAE improvements Robin Murphy
2019-09-11 14:42 ` Robin Murphy [this message]
2019-09-12 10:41   ` [PATCH 1/3] iommu/io-pgtable-arm: Correct Mali attributes Steven Price
2019-09-11 14:42 ` [PATCH 2/3] iommu/io-pgtable-arm: Support more Mali configurations Robin Murphy
2019-09-12 10:47   ` Steven Price
2019-09-11 14:42 ` [PATCH 3/3] iommu/io-pgtable-arm: Allow coherent walks for Mali Robin Murphy
2019-09-12 10:53   ` Steven Price
2019-09-11 16:19 ` [PATCH 0/3] iommu/io-pgtable-arm: Mali LPAE improvements Neil Armstrong
2019-09-11 16:20   ` Will Deacon
2019-09-11 17:19     ` Robin Murphy
2019-09-19  8:30       ` Will Deacon
2019-09-23  8:17         ` Tomeu Vizoso
2019-09-23 11:04           ` Robin Murphy

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