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[xen staging] xen/arm: smmuv1: Keep track of S2CR state



commit 06d1f7a278ddf4344efbb28c3360901b5a79ab75
Author:     Rahul Singh <rahul.singh@xxxxxxx>
AuthorDate: Mon Mar 22 16:11:37 2021 +0000
Commit:     Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Thu Apr 1 17:12:05 2021 +0100

    xen/arm: smmuv1: Keep track of S2CR state
    
    Backport commit 8e8b203eabd8b9e96d02d6339e4abce3e5a7ea4b
    "iommu/arm-smmu: Keep track of S2CR state" from the Linux kernel.
    
    This patch is the preparatory work to fix the stream match conflict
    when two devices have the same stream-id.
    
    Original commit message:
        iommu/arm-smmu: Keep track of S2CR state
    
        Making S2CRs first-class citizens within the driver with a high-level
        representation of their state offers a neat solution to a few problems:
    
        Firstly, the information about which context a device's stream IDs are
        associated with is already present by necessity in the S2CR. With that
        state easily accessible we can refer directly to it and obviate the need
        to track an IOMMU domain in each device's archdata (its earlier purpose
        of enforcing correct attachment of multi-device groups now being handled
        by the IOMMU core itself).
    
        Secondly, the core API now deprecates explicit domain detach and expects
        domain attach to move devices smoothly from one domain to another; for
        SMMUv2, this notion maps directly to simply rewriting the S2CRs assigned
        to the device. By giving the driver a suitable abstraction of those
        S2CRs to work with, we can massively reduce the overhead of the current
        heavy-handed "detach, free resources, reallocate resources, attach"
        approach.
    
        Thirdly, making the software state hardware-shaped and attached to the
        SMMU instance once again makes suspend/resume of this register group
        that much simpler to implement in future.
    
        Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
        Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
    
    Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
    Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
    Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
    Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
---
 xen/drivers/passthrough/arm/smmu.c | 150 ++++++++++++++++++++++---------------
 1 file changed, 89 insertions(+), 61 deletions(-)

diff --git a/xen/drivers/passthrough/arm/smmu.c 
b/xen/drivers/passthrough/arm/smmu.c
index c41e94f836..e1b937bd4b 100644
--- a/xen/drivers/passthrough/arm/smmu.c
+++ b/xen/drivers/passthrough/arm/smmu.c
@@ -444,9 +444,20 @@ static struct iommu_group *iommu_group_get(struct device 
*dev)
 #define S2CR_CBNDX_MASK                        0xff
 #define S2CR_TYPE_SHIFT                        16
 #define S2CR_TYPE_MASK                 0x3
-#define S2CR_TYPE_TRANS                        (0 << S2CR_TYPE_SHIFT)
-#define S2CR_TYPE_BYPASS               (1 << S2CR_TYPE_SHIFT)
-#define S2CR_TYPE_FAULT                        (2 << S2CR_TYPE_SHIFT)
+enum arm_smmu_s2cr_type {
+       S2CR_TYPE_TRANS,
+       S2CR_TYPE_BYPASS,
+       S2CR_TYPE_FAULT,
+};
+
+#define S2CR_PRIVCFG_SHIFT             24
+#define S2CR_PRIVCFG_MASK              0x3
+enum arm_smmu_s2cr_privcfg {
+       S2CR_PRIVCFG_DEFAULT,
+       S2CR_PRIVCFG_DIPAN,
+       S2CR_PRIVCFG_UNPRIV,
+       S2CR_PRIVCFG_PRIV,
+};
 
 /* Context bank attribute registers */
 #define ARM_SMMU_GR1_CBAR(n)           (0x0 + ((n) << 2))
@@ -585,6 +596,16 @@ enum arm_smmu_arch_version {
        ARM_SMMU_V2,
 };
 
+struct arm_smmu_s2cr {
+       enum arm_smmu_s2cr_type         type;
+       enum arm_smmu_s2cr_privcfg      privcfg;
+       u8                              cbndx;
+};
+
+#define s2cr_init_val (struct arm_smmu_s2cr){                          \
+       .type = S2CR_TYPE_FAULT                                 \
+}
+
 struct arm_smmu_smr {
        u16                             mask;
        u16                             id;
@@ -631,6 +652,7 @@ struct arm_smmu_device {
        u16                             streamid_mask;
        u16                             smr_mask_mask;
        struct arm_smmu_smr             *smrs;
+       struct arm_smmu_s2cr            *s2crs;
 
        unsigned long                   s1_input_size;
        unsigned long                   s1_output_size;
@@ -1411,6 +1433,23 @@ static void arm_smmu_write_smr(struct arm_smmu_device 
*smmu, int idx)
        writel_relaxed(reg, ARM_SMMU_GR0(smmu) + ARM_SMMU_GR0_SMR(idx));
 }
 
+static void arm_smmu_write_s2cr(struct arm_smmu_device *smmu, int idx)
+{
+       struct arm_smmu_s2cr *s2cr = smmu->s2crs + idx;
+       u32 reg = (s2cr->type & S2CR_TYPE_MASK) << S2CR_TYPE_SHIFT |
+                 (s2cr->cbndx & S2CR_CBNDX_MASK) << S2CR_CBNDX_SHIFT |
+                 (s2cr->privcfg & S2CR_PRIVCFG_MASK) << S2CR_PRIVCFG_SHIFT;
+
+       writel_relaxed(reg, ARM_SMMU_GR0(smmu) + ARM_SMMU_GR0_S2CR(idx));
+}
+
+static void arm_smmu_write_sme(struct arm_smmu_device *smmu, int idx)
+{
+       arm_smmu_write_s2cr(smmu, idx);
+       if (smmu->smrs)
+               arm_smmu_write_smr(smmu, idx);
+}
+
 static int arm_smmu_master_alloc_smes(struct arm_smmu_device *smmu,
                                      struct arm_smmu_master_cfg *cfg)
 {
@@ -1461,6 +1500,23 @@ static void arm_smmu_master_free_smes(struct 
arm_smmu_device *smmu,
 {
        int i;
 
+       /*
+        * We *must* clear the S2CR first, because freeing the SMR means
+        * that it can be re-allocated immediately.
+        */
+       for (i = 0; i < cfg->num_streamids; ++i) {
+               int idx = cfg->smendx[i];
+
+               /* An IOMMU group is torn down by the first device to be 
removed */
+               if (idx == INVALID_SMENDX)
+                       return;
+
+               smmu->s2crs[idx] = s2cr_init_val;
+               arm_smmu_write_s2cr(smmu, idx);
+       }
+       /* Sync S2CR updates before touching anything else */
+       __iowmb();
+
        /* Invalidate the SMRs before freeing back to the allocator */
        for (i = 0; i < cfg->num_streamids; ++i) {
                if (smmu->smrs)
@@ -1473,51 +1529,30 @@ static void arm_smmu_master_free_smes(struct 
arm_smmu_device *smmu,
 static int arm_smmu_domain_add_master(struct arm_smmu_domain *smmu_domain,
                                      struct arm_smmu_master_cfg *cfg)
 {
-       int i, ret;
+       int i, ret = 0;
        struct arm_smmu_device *smmu = smmu_domain->smmu;
-       void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
+       struct arm_smmu_s2cr *s2cr = smmu->s2crs;
+       enum arm_smmu_s2cr_type type = S2CR_TYPE_TRANS;
+       u8 cbndx = smmu_domain->cfg.cbndx;
 
-       /* Devices in an IOMMU group may already be configured */
-       ret = arm_smmu_master_alloc_smes(smmu, cfg);
+       if (cfg->smendx[0] == INVALID_SMENDX)
+               ret = arm_smmu_master_alloc_smes(smmu, cfg);
        if (ret)
-               return ret == -EEXIST ? 0 : ret;
-
-       for (i = 0; i < cfg->num_streamids; ++i) {
-               u32 idx, s2cr;
-
-               idx = cfg->smendx[i];
-               s2cr = S2CR_TYPE_TRANS |
-                      (smmu_domain->cfg.cbndx << S2CR_CBNDX_SHIFT);
-               writel_relaxed(s2cr, gr0_base + ARM_SMMU_GR0_S2CR(idx));
-       }
-
-       return 0;
-}
-
-static void arm_smmu_domain_remove_master(struct arm_smmu_domain *smmu_domain,
-                                         struct arm_smmu_master_cfg *cfg)
-{
-       int i;
-       struct arm_smmu_device *smmu = smmu_domain->smmu;
-       void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
+               return ret;
 
-       /*
-        * We *must* clear the S2CR first, because freeing the SMR means
-        * that it can be re-allocated immediately.
-        * Xen: Unlike Linux, any access to non-configured stream will fault.
-        */
        for (i = 0; i < cfg->num_streamids; ++i) {
                int idx = cfg->smendx[i];
 
-               /* An IOMMU group is torn down by the first device to be 
removed */
-               if (idx == INVALID_SMENDX)
-                       return;
+               /* Devices in an IOMMU group may already be configured */
+               if (type == s2cr[idx].type && cbndx == s2cr[idx].cbndx)
+                       break;
 
-               writel_relaxed(S2CR_TYPE_FAULT,
-                              gr0_base + ARM_SMMU_GR0_S2CR(idx));
+               s2cr[idx].type = type ;
+               s2cr[idx].privcfg = S2CR_PRIVCFG_UNPRIV;
+               s2cr[idx].cbndx = cbndx;
+               arm_smmu_write_s2cr(smmu, idx);
        }
-
-       arm_smmu_master_free_smes(smmu, cfg);
+       return 0;
 }
 
 static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
@@ -1564,24 +1599,17 @@ static int arm_smmu_attach_dev(struct iommu_domain 
*domain, struct device *dev)
        if (!cfg)
                return -ENODEV;
 
-       ret = arm_smmu_domain_add_master(smmu_domain, cfg);
-
-       if (!ret)
-               dev_iommu_domain(dev) = domain;
-       return ret;
+       return arm_smmu_domain_add_master(smmu_domain, cfg);
 }
 
 static void arm_smmu_detach_dev(struct iommu_domain *domain, struct device 
*dev)
 {
-       struct arm_smmu_domain *smmu_domain = domain->priv;
-       struct arm_smmu_master_cfg *cfg;
+       struct arm_smmu_device *smmu = find_smmu_for_device(dev);
+       struct arm_smmu_master_cfg *cfg = find_smmu_master_cfg(dev);
 
-       cfg = find_smmu_master_cfg(dev);
-       if (!cfg)
-               return;
+       if (smmu && cfg)
+               arm_smmu_master_free_smes(smmu, cfg);
 
-       dev_iommu_domain(dev) = NULL;
-       arm_smmu_domain_remove_master(smmu_domain, cfg);
 }
 
 #if 0 /*
@@ -2039,16 +2067,8 @@ static void arm_smmu_device_reset(struct arm_smmu_device 
*smmu)
         * Reset stream mapping groups: Initial values mark all SMRn as
         * invalid and all S2CRn as bypass unless overridden.
         */
-       for (i = 0; i < smmu->num_mapping_groups; ++i) {
-               if (smmu->smrs)
-                       arm_smmu_write_smr(smmu, i);
-               /*
-                * Xen: Unlike Linux, any access to a non-configure stream
-                * will fault by default.
-                */
-               writel_relaxed(S2CR_TYPE_FAULT,
-                       gr0_base + ARM_SMMU_GR0_S2CR(i));
-       }
+       for (i = 0; i < smmu->num_mapping_groups; ++i)
+               arm_smmu_write_sme(smmu, i);
 
        /* Make sure all context banks are disabled and clear CB_FSR  */
        for (i = 0; i < smmu->num_context_banks; ++i) {
@@ -2110,6 +2130,7 @@ static int arm_smmu_device_cfg_probe(struct 
arm_smmu_device *smmu)
        unsigned long size;
        void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
        u32 id;
+       int i;
 
        dev_notice(smmu->dev, "probing hardware configuration...\n");
        dev_notice(smmu->dev, "SMMUv%d with:\n", smmu->version);
@@ -2193,6 +2214,13 @@ static int arm_smmu_device_cfg_probe(struct 
arm_smmu_device *smmu)
                           "\tstream matching with %lu register groups, mask 
0x%x",
                           size, smmu->smr_mask_mask);
        }
+       /* s2cr->type == 0 means translation, so initialise explicitly */
+       smmu->s2crs = kmalloc_array(size, sizeof(*smmu->s2crs), GFP_KERNEL);
+       if (!smmu->s2crs)
+               return -ENOMEM;
+       for (i = 0; i < size; i++)
+               smmu->s2crs[i] = s2cr_init_val;
+
        smmu->num_mapping_groups = size;
 
        /* ID1 */
--
generated by git-patchbot for /home/xen/git/xen.git#staging



 


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