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xen/arm: smmuv1: Consolidate stream map entry state
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Backport commit 1f3d5ca43019bff1105838712d55be087d93c0da
"iommu/arm-smmu: Consolidate stream map entry 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: Consolidate stream map entry state

    In order to consider SMR masking, we really want to be able to validate
    ID/mask pairs against existing SMR contents to prevent stream match
    conflicts, which at best would cause transactions to fault unexpectedly,
    and at worst lead to silent unpredictable behaviour. With our SMMU
    instance data holding only an allocator bitmap, and the SMR values
    themselves scattered across master configs hanging off devices which we
    may have no way of finding, there's essentially no way short of digging
    everything back out of the hardware. Similarly, the thought of power
    management ops to support suspend/resume faces the exact same problem.

    By massaging the software state into a closer shape to the underlying
    hardware, everything comes together quite nicely; the allocator and the
    high-level view of the data become a single centralised state which we
    can easily keep track of, and to which any updates can be validated in
    full before being synchronised to the hardware itself.

    Signed-off-by: Robin Murphy <robin.murphy@arm.com>
    Signed-off-by: Will Deacon <will.deacon@arm.com>

Signed-off-by: Rahul Singh <rahul.singh@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>
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@rahul-sin
rahul-sin authored and Julien Grall committed Apr 1, 2021
1 parent e889809 commit 5e08586
Showing 1 changed file with 79 additions and 59 deletions.
138 changes: 79 additions & 59 deletions xen/drivers/passthrough/arm/smmu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -308,9 +308,6 @@ static struct iommu_group *iommu_group_get(struct device *dev)
/* Maximum number of context banks per SMMU */
#define ARM_SMMU_MAX_CBS 128

/* Maximum number of mapping groups per SMMU */
#define ARM_SMMU_MAX_SMRS 128

/* SMMU global address space */
#define ARM_SMMU_GR0(smmu) ((smmu)->base)
#define ARM_SMMU_GR1(smmu) ((smmu)->base + (1 << (smmu)->pgshift))
Expand Down Expand Up @@ -589,16 +586,17 @@ enum arm_smmu_arch_version {
};

struct arm_smmu_smr {
u8 idx;
u16 mask;
u16 id;
bool valid;
};

struct arm_smmu_master_cfg {
int num_streamids;
u16 streamids[MAX_MASTER_STREAMIDS];
struct arm_smmu_smr *smrs;
s16 smendx[MAX_MASTER_STREAMIDS];
};
#define INVALID_SMENDX -1

struct arm_smmu_master {
struct device_node *of_node;
Expand Down Expand Up @@ -632,7 +630,7 @@ struct arm_smmu_device {
u32 num_mapping_groups;
u16 streamid_mask;
u16 smr_mask_mask;
DECLARE_BITMAP(smr_map, ARM_SMMU_MAX_SMRS);
struct arm_smmu_smr *smrs;

unsigned long s1_input_size;
unsigned long s1_output_size;
Expand Down Expand Up @@ -818,6 +816,7 @@ static int register_smmu_master(struct arm_smmu_device *smmu,
return -ERANGE;
}
master->cfg.streamids[i] = streamid;
master->cfg.smendx[i] = INVALID_SMENDX;
}
return insert_smmu_master(smmu, master);
}
Expand Down Expand Up @@ -1384,79 +1383,91 @@ static void arm_smmu_domain_destroy(struct iommu_domain *domain)
kfree(smmu_domain);
}

static int arm_smmu_master_configure_smrs(struct arm_smmu_device *smmu,
struct arm_smmu_master_cfg *cfg)
static int arm_smmu_alloc_smr(struct arm_smmu_device *smmu)
{
int i;
struct arm_smmu_smr *smrs;
void __iomem *gr0_base = ARM_SMMU_GR0(smmu);

if (!(smmu->features & ARM_SMMU_FEAT_STREAM_MATCH))
return 0;
for (i = 0; i < smmu->num_mapping_groups; i++)
if (!cmpxchg(&smmu->smrs[i].valid, false, true))
return i;

if (cfg->smrs)
return -EEXIST;
return INVALID_SMENDX;
}

smrs = kmalloc_array(cfg->num_streamids, sizeof(*smrs), GFP_KERNEL);
if (!smrs) {
dev_err(smmu->dev, "failed to allocate %d SMRs\n",
cfg->num_streamids);
return -ENOMEM;
}
static void arm_smmu_free_smr(struct arm_smmu_device *smmu, int idx)
{
writel_relaxed(~SMR_VALID, ARM_SMMU_GR0(smmu) + ARM_SMMU_GR0_SMR(idx));
write_atomic(&smmu->smrs[idx].valid, false);
}

static void arm_smmu_write_smr(struct arm_smmu_device *smmu, int idx)
{
struct arm_smmu_smr *smr = smmu->smrs + idx;
u32 reg = (smr->id & smmu->streamid_mask) << SMR_ID_SHIFT |
(smr->mask & smmu->smr_mask_mask) << SMR_MASK_SHIFT;

if (smr->valid)
reg |= SMR_VALID;
writel_relaxed(reg, ARM_SMMU_GR0(smmu) + ARM_SMMU_GR0_SMR(idx));
}

static int arm_smmu_master_alloc_smes(struct arm_smmu_device *smmu,
struct arm_smmu_master_cfg *cfg)
{
struct arm_smmu_smr *smrs = smmu->smrs;
int i, idx;

/* Allocate the SMRs on the SMMU */
for (i = 0; i < cfg->num_streamids; ++i) {
int idx = __arm_smmu_alloc_bitmap(smmu->smr_map, 0,
smmu->num_mapping_groups);
if (cfg->smendx[i] != INVALID_SMENDX)
return -EEXIST;

/* ...except on stream indexing hardware, of course */
if (!smrs) {
cfg->smendx[i] = cfg->streamids[i];
continue;
}

idx = arm_smmu_alloc_smr(smmu);
if (IS_ERR_VALUE(idx)) {
dev_err(smmu->dev, "failed to allocate free SMR\n");
goto err_free_smrs;
}
cfg->smendx[i] = idx;

smrs[i] = (struct arm_smmu_smr) {
.idx = idx,
.mask = 0, /* We don't currently share SMRs */
.id = cfg->streamids[i],
};
smrs[idx].id = cfg->streamids[i];
smrs[idx].mask = 0; /* We don't currently share SMRs */
}

if (!smrs)
return 0;

/* It worked! Now, poke the actual hardware */
for (i = 0; i < cfg->num_streamids; ++i) {
u32 reg = SMR_VALID | smrs[i].id << SMR_ID_SHIFT |
smrs[i].mask << SMR_MASK_SHIFT;
writel_relaxed(reg, gr0_base + ARM_SMMU_GR0_SMR(smrs[i].idx));
}
for (i = 0; i < cfg->num_streamids; ++i)
arm_smmu_write_smr(smmu, cfg->smendx[i]);

cfg->smrs = smrs;
return 0;

err_free_smrs:
while (--i >= 0)
__arm_smmu_free_bitmap(smmu->smr_map, smrs[i].idx);
kfree(smrs);
while (i--) {
arm_smmu_free_smr(smmu, cfg->smendx[i]);
cfg->smendx[i] = INVALID_SMENDX;
}
return -ENOSPC;
}

static void arm_smmu_master_free_smrs(struct arm_smmu_device *smmu,
static void arm_smmu_master_free_smes(struct arm_smmu_device *smmu,
struct arm_smmu_master_cfg *cfg)
{
int i;
void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
struct arm_smmu_smr *smrs = cfg->smrs;

if (!smrs)
return;

/* Invalidate the SMRs before freeing back to the allocator */
for (i = 0; i < cfg->num_streamids; ++i) {
u8 idx = smrs[i].idx;
if (smmu->smrs)
arm_smmu_free_smr(smmu, cfg->smendx[i]);

writel_relaxed(~SMR_VALID, gr0_base + ARM_SMMU_GR0_SMR(idx));
__arm_smmu_free_bitmap(smmu->smr_map, idx);
cfg->smendx[i] = INVALID_SMENDX;
}

cfg->smrs = NULL;
kfree(smrs);
}

static int arm_smmu_domain_add_master(struct arm_smmu_domain *smmu_domain,
Expand All @@ -1467,14 +1478,14 @@ static int arm_smmu_domain_add_master(struct arm_smmu_domain *smmu_domain,
void __iomem *gr0_base = ARM_SMMU_GR0(smmu);

/* Devices in an IOMMU group may already be configured */
ret = arm_smmu_master_configure_smrs(smmu, cfg);
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->smrs ? cfg->smrs[i].idx : cfg->streamids[i];
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));
Expand All @@ -1490,23 +1501,23 @@ static void arm_smmu_domain_remove_master(struct arm_smmu_domain *smmu_domain,
struct arm_smmu_device *smmu = smmu_domain->smmu;
void __iomem *gr0_base = ARM_SMMU_GR0(smmu);

/* An IOMMU group is torn down by the first device to be removed */
if ((smmu->features & ARM_SMMU_FEAT_STREAM_MATCH) && !cfg->smrs)
return;

/*
* 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) {
u32 idx = cfg->smrs ? cfg->smrs[i].idx : cfg->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;

writel_relaxed(S2CR_TYPE_FAULT,
gr0_base + ARM_SMMU_GR0_S2CR(idx));
}

arm_smmu_master_free_smrs(smmu, cfg);
arm_smmu_master_free_smes(smmu, cfg);
}

static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
Expand Down Expand Up @@ -2017,16 +2028,20 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
{
void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
void __iomem *cb_base;
int i = 0;
int i;
u32 reg;

/* clear global FSR */
reg = readl_relaxed(ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sGFSR);
writel(reg, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sGFSR);

/* Mark all SMRn as invalid and all S2CRn as bypass */
/*
* 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) {
writel_relaxed(0, gr0_base + ARM_SMMU_GR0_SMR(i));
if (smmu->smrs)
arm_smmu_write_smr(smmu, i);
/*
* Xen: Unlike Linux, any access to a non-configure stream
* will fault by default.
Expand Down Expand Up @@ -2169,6 +2184,11 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
smr = readl_relaxed(gr0_base + ARM_SMMU_GR0_SMR(0));
smmu->smr_mask_mask = smr >> SMR_MASK_SHIFT;

/* Zero-initialised to mark as invalid */
smmu->smrs = devm_kzalloc(smmu->dev, sizeof(*smmu->smrs), GFP_KERNEL);
if (!smmu->smrs)
return -ENOMEM;

dev_notice(smmu->dev,
"\tstream matching with %lu register groups, mask 0x%x",
size, smmu->smr_mask_mask);
Expand Down

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