iommu/arm-smmu-v3: Manage ASIDs with xarray

In preparation for sharing some ASIDs with the CPU, use a global xarray to
store ASIDs and their context. ASID#0 is now reserved, and the ASID
space is global.
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20200519175502.2504091-9-jean-philippe@linaro.orgSigned-off-by: Will Deacon <will@kernel.org>

drivers/iommu/arm-smmu-v3.c

@@ -667,7 +667,6 @@ struct arm_smmu_device {
 
 #define ARM_SMMU_MAX_ASIDS		(1 << 16)
 	unsigned int			asid_bits;
-	DECLARE_BITMAP(asid_map, ARM_SMMU_MAX_ASIDS);
 
 #define ARM_SMMU_MAX_VMIDS		(1 << 16)
 	unsigned int			vmid_bits;
@@ -727,6 +726,8 @@ struct arm_smmu_option_prop {
 	const char *prop;
 };
 
+static DEFINE_XARRAY_ALLOC1(asid_xa);
+
 static struct arm_smmu_option_prop arm_smmu_options[] = {
 	{ ARM_SMMU_OPT_SKIP_PREFETCH, "hisilicon,broken-prefetch-cmd" },
 	{ ARM_SMMU_OPT_PAGE0_REGS_ONLY, "cavium,cn9900-broken-page1-regspace"},
@@ -1765,6 +1766,14 @@ static void arm_smmu_free_cd_tables(struct arm_smmu_domain *smmu_domain)
 	cdcfg->cdtab = NULL;
 }
 
+static void arm_smmu_free_asid(struct arm_smmu_ctx_desc *cd)
+{
+	if (!cd->asid)
+		return;
+
+	xa_erase(&asid_xa, cd->asid);
+}
+
 /* Stream table manipulation functions */
 static void
 arm_smmu_write_strtab_l1_desc(__le64 *dst, struct arm_smmu_strtab_l1_desc *desc)
@@ -2450,10 +2459,9 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
 	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
 		struct arm_smmu_s1_cfg *cfg = &smmu_domain->s1_cfg;
 
-		if (cfg->cdcfg.cdtab) {
+		if (cfg->cdcfg.cdtab)
 			arm_smmu_free_cd_tables(smmu_domain);
-			arm_smmu_bitmap_free(smmu->asid_map, cfg->cd.asid);
-		}
+		arm_smmu_free_asid(&cfg->cd);
 	} else {
 		struct arm_smmu_s2_cfg *cfg = &smmu_domain->s2_cfg;
 		if (cfg->vmid)
@@ -2468,14 +2476,15 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
 				       struct io_pgtable_cfg *pgtbl_cfg)
 {
 	int ret;
-	int asid;
+	u32 asid;
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
 	struct arm_smmu_s1_cfg *cfg = &smmu_domain->s1_cfg;
 	typeof(&pgtbl_cfg->arm_lpae_s1_cfg.tcr) tcr = &pgtbl_cfg->arm_lpae_s1_cfg.tcr;
 
-	asid = arm_smmu_bitmap_alloc(smmu->asid_map, smmu->asid_bits);
-	if (asid < 0)
-		return asid;
+	ret = xa_alloc(&asid_xa, &asid, &cfg->cd,
+		       XA_LIMIT(1, (1 << smmu->asid_bits) - 1), GFP_KERNEL);
+	if (ret)
+		return ret;
 
 	cfg->s1cdmax = master->ssid_bits;
 
@@ -2508,7 +2517,7 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
 out_free_cd_tables:
 	arm_smmu_free_cd_tables(smmu_domain);
 out_free_asid:
-	arm_smmu_bitmap_free(smmu->asid_map, asid);
+	arm_smmu_free_asid(&cfg->cd);
 	return ret;
 }