Commit f322e8af authored by Robin Murphy's avatar Robin Murphy Committed by Will Deacon
Browse files

iommu/arm-smmu-v3: Work around MMU-600 erratum 1076982 



MMU-600 versions prior to r1p0 fail to correctly generate a WFE wakeup
event when the command queue transitions fom full to non-full. We can
easily work around this by simply hiding the SEV capability such that we
fall back to polling for space in the queue - since MMU-600 implements
MSIs we wouldn't expect to need SEV for sync completion either, so this
should have little to no impact.

Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Reviewed-by: default avatarNicolin Chen <nicolinc@nvidia.com>
Tested-by: default avatarNicolin Chen <nicolinc@nvidia.com>
Link: https://lore.kernel.org/r/08adbe3d01024d8382a478325f73b56851f76e49.1683731256.git.robin.murphy@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 44c026a7

Documentation/arm64/silicon-errata.rst

+2 −0
Original line number Diff line number Diff line
@@ -140,6 +140,8 @@ stable kernels. 
+----------------+-----------------+-----------------+-----------------------------+

| ARM            | MMU-500         | #841119,826419  | N/A                         |

+----------------+-----------------+-----------------+-----------------------------+

| ARM            | MMU-600         | #1076982        | N/A                         |

+----------------+-----------------+-----------------+-----------------------------+

+----------------+-----------------+-----------------+-----------------------------+

| Broadcom       | Brahma-B53      | N/A             | ARM64_ERRATUM_845719        |

+----------------+-----------------+-----------------+-----------------------------+

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

+29 −0
Original line number Diff line number Diff line
@@ -3429,6 +3429,33 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass) 
	return 0;

}



#define IIDR_IMPLEMENTER_ARM		0x43b

#define IIDR_PRODUCTID_ARM_MMU_600	0x483



static void arm_smmu_device_iidr_probe(struct arm_smmu_device *smmu)

{

	u32 reg;

	unsigned int implementer, productid, variant, revision;



	reg = readl_relaxed(smmu->base + ARM_SMMU_IIDR);

	implementer = FIELD_GET(IIDR_IMPLEMENTER, reg);

	productid = FIELD_GET(IIDR_PRODUCTID, reg);

	variant = FIELD_GET(IIDR_VARIANT, reg);

	revision = FIELD_GET(IIDR_REVISION, reg);



	switch (implementer) {

	case IIDR_IMPLEMENTER_ARM:

		switch (productid) {

		case IIDR_PRODUCTID_ARM_MMU_600:

			/* Arm erratum 1076982 */

			if (variant == 0 && revision <= 2)

				smmu->features &= ~ARM_SMMU_FEAT_SEV;

			break;

		}

		break;

	}

}



static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)

{

	u32 reg;
@@ -3635,6 +3662,8 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu) 


	smmu->ias = max(smmu->ias, smmu->oas);



	arm_smmu_device_iidr_probe(smmu);



	if (arm_smmu_sva_supported(smmu))

		smmu->features |= ARM_SMMU_FEAT_SVA;

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h

+6 −0
Original line number Diff line number Diff line
@@ -69,6 +69,12 @@ 
#define IDR5_VAX			GENMASK(11, 10)

#define IDR5_VAX_52_BIT			1



#define ARM_SMMU_IIDR			0x18

#define IIDR_PRODUCTID			GENMASK(31, 20)

#define IIDR_VARIANT			GENMASK(19, 16)

#define IIDR_REVISION			GENMASK(15, 12)

#define IIDR_IMPLEMENTER		GENMASK(11, 0)



#define ARM_SMMU_CR0			0x20

#define CR0_ATSCHK			(1 << 4)

#define CR0_CMDQEN			(1 << 3)