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[RFCv2,26/36] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update

Message ID 20171006133203.22803-27-jean-philippe.brucker@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jean-Philippe Brucker Oct. 6, 2017, 1:31 p.m. UTC 
If the SMMU supports it and the kernel was built with HTTU support, enable
hardware update of access and dirty flags. This is essential for shared
page tables, to reduce the number of access faults on the fault queue.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
---
 drivers/iommu/arm-smmu-v3.c | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

Comments

Xie Yisheng Dec. 6, 2017, 6:51 a.m. UTC | #1 
Hi Jean,

On 2017/10/6 21:31, Jean-Philippe Brucker wrote:
> If the SMMU supports it and the kernel was built with HTTU support, enable
> +	if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM) && (reg & (IDR0_HA | IDR0_HD))) {
> +		smmu->features |= ARM_SMMU_FEAT_HA;
> +		if (reg & IDR0_HD)
> +			smmu->features |= ARM_SMMU_FEAT_HD;
> +	}

What is relationship of armv8.1 HW_AFDBM and SMMUv3 HTTU? I mean why we need
IS_ENABLED(CONFIG_ARM64_HW_AFDBM) ?

If CONFIG_ARM64_HW_AFDBM=y but the process do not support ARMv8.1, should it also
enable related feature for SMMUv3?

Thanks
Yisheng Xie
> +
>  	/*
>  	 * If the CPU is using VHE, but the SMMU doesn't support it, the SMMU
>  	 * will create TLB entries for NH-EL1 world and will miss the
>
Jean-Philippe Brucker Dec. 6, 2017, 11:06 a.m. UTC | #2 
On 06/12/17 06:51, Yisheng Xie wrote:
> Hi Jean,
> 
> On 2017/10/6 21:31, Jean-Philippe Brucker wrote:
>> If the SMMU supports it and the kernel was built with HTTU support, enable
>> +	if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM) && (reg & (IDR0_HA | IDR0_HD))) {
>> +		smmu->features |= ARM_SMMU_FEAT_HA;
>> +		if (reg & IDR0_HD)
>> +			smmu->features |= ARM_SMMU_FEAT_HD;
>> +	}
> 
> What is relationship of armv8.1 HW_AFDBM and SMMUv3 HTTU? I mean why we need
> IS_ENABLED(CONFIG_ARM64_HW_AFDBM) ?

I think the reason we needed this was that, without CONFIG_ARM64_HW_AFDBM,
the CPU wouldn't update the pte atomically and pte_dirty() wouldn't check
the DBM bit 51 (only the SW dirty bit 55).

Since af29678fe785 ("arm64: Remove the !CONFIG_ARM64_HW_AFDBM alternative
code paths") removed lots of #ifdefs, I'll see if we can remove the above
IS_ENABLED as well.

> If CONFIG_ARM64_HW_AFDBM=y but the process do not support ARMv8.1, should it also
> enable related feature for SMMUv3?

Yes I think we can enable HTTU in the SMMU even if the CPU doesn't support
it (though HTTU is only useful when sharing process address spaces). The
mm code checks for both HW and SW bits even when the CPU doesn't support
ARMv8.1

Thanks,
Jean
diff mbox

Patch

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index b7355630526a..2b2e2be03de7 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -67,6 +67,8 @@ 
 #define IDR0_ASID16			(1 << 12)
 #define IDR0_ATS			(1 << 10)
 #define IDR0_HYP			(1 << 9)
+#define IDR0_HD				(1 << 7)
+#define IDR0_HA				(1 << 6)
 #define IDR0_BTM			(1 << 5)
 #define IDR0_COHACC			(1 << 4)
 #define IDR0_TTF_SHIFT			2
@@ -342,7 +344,16 @@ 
 #define ARM64_TCR_TBI0_SHIFT		37
 #define ARM64_TCR_TBI0_MASK		0x1UL
 
+#define ARM64_TCR_HA_SHIFT		39
+#define ARM64_TCR_HA_MASK		0x1UL
+#define ARM64_TCR_HD_SHIFT		40
+#define ARM64_TCR_HD_MASK		0x1UL
+
 #define CTXDESC_CD_0_AA64		(1UL << 41)
+#define CTXDESC_CD_0_TCR_HD_SHIFT	42
+#define CTXDESC_CD_0_TCR_HA_SHIFT	43
+#define CTXDESC_CD_0_HD			(1UL << CTXDESC_CD_0_TCR_HD_SHIFT)
+#define CTXDESC_CD_0_HA			(1UL << CTXDESC_CD_0_TCR_HA_SHIFT)
 #define CTXDESC_CD_0_S			(1UL << 44)
 #define CTXDESC_CD_0_R			(1UL << 45)
 #define CTXDESC_CD_0_A			(1UL << 46)
@@ -670,6 +681,8 @@  struct arm_smmu_device {
 #define ARM_SMMU_FEAT_E2H		(1 << 14)
 #define ARM_SMMU_FEAT_BTM		(1 << 15)
 #define ARM_SMMU_FEAT_SVM		(1 << 16)
+#define ARM_SMMU_FEAT_HA		(1 << 17)
+#define ARM_SMMU_FEAT_HD		(1 << 18)
 	u32				features;
 
 #define ARM_SMMU_OPT_SKIP_PREFETCH	(1 << 0)
@@ -1157,7 +1170,7 @@  static __u64 *arm_smmu_get_cd_ptr(struct arm_smmu_domain *smmu_domain, u32 ssid)
 	return l1_desc->cdptr + idx * CTXDESC_CD_DWORDS;
 }
 
-static u64 arm_smmu_cpu_tcr_to_cd(u64 tcr)
+static u64 arm_smmu_cpu_tcr_to_cd(struct arm_smmu_device *smmu, u64 tcr)
 {
 	u64 val = 0;
 
@@ -1172,6 +1185,12 @@  static u64 arm_smmu_cpu_tcr_to_cd(u64 tcr)
 	val |= ARM_SMMU_TCR2CD(tcr, IPS);
 	val |= ARM_SMMU_TCR2CD(tcr, TBI0);
 
+	if (smmu->features & ARM_SMMU_FEAT_HA)
+		val |= ARM_SMMU_TCR2CD(tcr, HA);
+
+	if (smmu->features & ARM_SMMU_FEAT_HD)
+		val |= ARM_SMMU_TCR2CD(tcr, HD);
+
 	return val;
 }
 
@@ -1235,7 +1254,7 @@  static void arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain,
 			 */
 			arm_smmu_sync_cd(smmu_domain, ssid, true);
 
-		val = arm_smmu_cpu_tcr_to_cd(cd->tcr) |
+		val = arm_smmu_cpu_tcr_to_cd(smmu_domain->smmu, cd->tcr) |
 #ifdef __BIG_ENDIAN
 		      CTXDESC_CD_0_ENDI |
 #endif
@@ -2203,8 +2222,7 @@  static int arm_smmu_process_init_pgtable(struct arm_smmu_process *smmu_process,
 	reg = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
 	par = cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR0_PARANGE_SHIFT);
 	tcr |= par << ARM_LPAE_TCR_IPS_SHIFT;
-
-	tcr |= TCR_TBI0;
+	tcr |= TCR_TBI0 | TCR_HA | TCR_HD;
 
 	cfg->asid       = asid;
 	cfg->ttbr       = virt_to_phys(mm->pgd);
@@ -3275,6 +3293,12 @@  static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
 			smmu->features |= ARM_SMMU_FEAT_E2H;
 	}
 
+	if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM) && (reg & (IDR0_HA | IDR0_HD))) {
+		smmu->features |= ARM_SMMU_FEAT_HA;
+		if (reg & IDR0_HD)
+			smmu->features |= ARM_SMMU_FEAT_HD;
+	}
+
 	/*
 	 * If the CPU is using VHE, but the SMMU doesn't support it, the SMMU
 	 * will create TLB entries for NH-EL1 world and will miss the