[PATCH v8 6/6] iommu/tegra241-cmdqv: Limit CMDs for guest owned VINTF

From: Nicolin Chen
Date: Tue May 28 2024 - 04:12:20 EST


When VCMDQs are assigned to a VINTF owned by a guest (HYP_OWN bit unset),
only TLB and ATC invalidation commands are supported by the VCMDQ HW. So,
add a new helper to scan the input cmd to make sure it is supported when
selecting a queue, though this assumes that SMMUv3 driver will only add
the same type of commands into an arm_smmu_cmdq_batch as it does today.

Note that the guest VM shouldn't have HYP_OWN bit being set regardless of
guest kernel driver writing it or not, i.e. the hypervisor running in the
host OS should wire this bit to zero when trapping a write access to this
VINTF_CONFIG register from a guest kernel.

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 31 +++++++++++-----
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 5 +--
.../iommu/arm/arm-smmu-v3/tegra241-cmdqv.c | 36 ++++++++++++++++++-
3 files changed, 60 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 430e84fe3679..3e2eb88535de 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -332,10 +332,22 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
return 0;
}

-static struct arm_smmu_cmdq *arm_smmu_get_cmdq(struct arm_smmu_device *smmu)
+static struct arm_smmu_cmdq *
+arm_smmu_get_cmdq(struct arm_smmu_device *smmu, u8 opcode)
{
+ /*
+ * TEGRA241 CMDQV has two modes to execute commands: host and guest.
+ * The host mode supports all the opcodes, while the guest mode only
+ * supports a few invalidation ones (check tegra241_vintf_support_cmd)
+ * and also a CMD_SYNC added by arm_smmu_cmdq_issue_cmdlist(..., true).
+ *
+ * Here pass in the representing opcode for either a single command or
+ * an arm_smmu_cmdq_batch, assuming that this SMMU driver will only add
+ * same type of commands into a batch as it does today or it will only
+ * mix supported invalidation commands in a batch.
+ */
if (arm_smmu_has_tegra241_cmdqv(smmu))
- return tegra241_cmdqv_get_cmdq(smmu);
+ return tegra241_cmdqv_get_cmdq(smmu, opcode);

return &smmu->cmdq;
}
@@ -871,7 +883,7 @@ static int __arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu,
}

return arm_smmu_cmdq_issue_cmdlist(
- smmu, arm_smmu_get_cmdq(smmu), cmd, 1, sync);
+ smmu, arm_smmu_get_cmdq(smmu, ent->opcode), cmd, 1, sync);
}

static int arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu,
@@ -887,10 +899,11 @@ static int arm_smmu_cmdq_issue_cmd_with_sync(struct arm_smmu_device *smmu,
}

static void arm_smmu_cmdq_batch_init(struct arm_smmu_device *smmu,
- struct arm_smmu_cmdq_batch *cmds)
+ struct arm_smmu_cmdq_batch *cmds,
+ u8 opcode)
{
cmds->num = 0;
- cmds->cmdq = arm_smmu_get_cmdq(smmu);
+ cmds->cmdq = arm_smmu_get_cmdq(smmu, opcode);
}

static void arm_smmu_cmdq_batch_add(struct arm_smmu_device *smmu,
@@ -1169,7 +1182,7 @@ static void arm_smmu_sync_cd(struct arm_smmu_master *master,
},
};

- arm_smmu_cmdq_batch_init(smmu, &cmds);
+ arm_smmu_cmdq_batch_init(smmu, &cmds, cmd.opcode);
for (i = 0; i < master->num_streams; i++) {
cmd.cfgi.sid = master->streams[i].id;
arm_smmu_cmdq_batch_add(smmu, &cmds, &cmd);
@@ -2014,7 +2027,7 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master)

arm_smmu_atc_inv_to_cmd(IOMMU_NO_PASID, 0, 0, &cmd);

- arm_smmu_cmdq_batch_init(master->smmu, &cmds);
+ arm_smmu_cmdq_batch_init(master->smmu, &cmds, cmd.opcode);
for (i = 0; i < master->num_streams; i++) {
cmd.atc.sid = master->streams[i].id;
arm_smmu_cmdq_batch_add(master->smmu, &cmds, &cmd);
@@ -2054,7 +2067,7 @@ int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain, int ssid,

arm_smmu_atc_inv_to_cmd(ssid, iova, size, &cmd);

- arm_smmu_cmdq_batch_init(smmu_domain->smmu, &cmds);
+ arm_smmu_cmdq_batch_init(smmu_domain->smmu, &cmds, CMDQ_OP_ATC_INV);

spin_lock_irqsave(&smmu_domain->devices_lock, flags);
list_for_each_entry(master, &smmu_domain->devices, domain_head) {
@@ -2131,7 +2144,7 @@ static void __arm_smmu_tlb_inv_range(struct arm_smmu_cmdq_ent *cmd,
num_pages++;
}

- arm_smmu_cmdq_batch_init(smmu, &cmds);
+ arm_smmu_cmdq_batch_init(smmu, &cmds, cmd->opcode);

while (iova < end) {
if (smmu->features & ARM_SMMU_FEAT_RANGE_INV) {
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index 604e26a292e7..2c1fe7e129cd 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -879,7 +879,8 @@ struct tegra241_cmdqv *tegra241_cmdqv_acpi_probe(struct arm_smmu_device *smmu,
struct acpi_iort_node *node);
void tegra241_cmdqv_device_remove(struct arm_smmu_device *smmu);
int tegra241_cmdqv_device_reset(struct arm_smmu_device *smmu);
-struct arm_smmu_cmdq *tegra241_cmdqv_get_cmdq(struct arm_smmu_device *smmu);
+struct arm_smmu_cmdq *tegra241_cmdqv_get_cmdq(struct arm_smmu_device *smmu,
+ u8 opcode);
#else /* CONFIG_TEGRA241_CMDQV */
static inline bool arm_smmu_has_tegra241_cmdqv(struct arm_smmu_device *smmu)
{
@@ -903,7 +904,7 @@ static inline int tegra241_cmdqv_device_reset(struct arm_smmu_device *smmu)
}

static inline struct arm_smmu_cmdq *
-tegra241_cmdqv_get_cmdq(struct arm_smmu_device *smmu)
+tegra241_cmdqv_get_cmdq(struct arm_smmu_device *smmu, u8 opcode)
{
return NULL;
}
diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
index bec4275c18ca..fe7285e3a1c9 100644
--- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
+++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
@@ -144,6 +144,7 @@ struct tegra241_vcmdq {
* struct tegra241_vintf - Virtual Interface
* @idx: Global index in the CMDQV
* @enabled: Enable status
+ * @hyp_own: Owned by hypervisor (in-kernel)
* @cmdqv: Parent CMDQV pointer
* @lvcmdqs: List of logical VCMDQ pointers
* @base: MMIO base address
@@ -152,6 +153,7 @@ struct tegra241_vintf {
u16 idx;

bool enabled;
+ bool hyp_own;

struct tegra241_cmdqv *cmdqv;
struct tegra241_vcmdq **lvcmdqs;
@@ -290,7 +292,25 @@ static irqreturn_t tegra241_cmdqv_isr(int irq, void *devid)

/* Command Queue Selecting Function */

-struct arm_smmu_cmdq *tegra241_cmdqv_get_cmdq(struct arm_smmu_device *smmu)
+static bool tegra241_vintf_support_cmd(struct tegra241_vintf *vintf, u8 opcode)
+{
+ /* Hypervisor-owned VINTF can execute any command in its VCMDQs */
+ if (READ_ONCE(vintf->hyp_own))
+ return true;
+
+ /* Guest-owned VINTF must check against the list of supported CMDs */
+ switch (opcode) {
+ case CMDQ_OP_TLBI_NH_ASID:
+ case CMDQ_OP_TLBI_NH_VA:
+ case CMDQ_OP_ATC_INV:
+ return true;
+ default:
+ return false;
+ }
+}
+
+struct arm_smmu_cmdq *tegra241_cmdqv_get_cmdq(struct arm_smmu_device *smmu,
+ u8 opcode)
{
struct tegra241_cmdqv *cmdqv = smmu->tegra241_cmdqv;
struct tegra241_vintf *vintf = cmdqv->vintfs[0];
@@ -304,6 +324,10 @@ struct arm_smmu_cmdq *tegra241_cmdqv_get_cmdq(struct arm_smmu_device *smmu)
if (!READ_ONCE(vintf->enabled))
return &smmu->cmdq;

+ /* Unsupported CMD go for smmu->cmdq pathway */
+ if (!tegra241_vintf_support_cmd(vintf, opcode))
+ return &smmu->cmdq;
+
/*
* Select a LVCMDQ to use. Here we use a temporal solution to
* balance out traffic on cmdq issuing: each cmdq has its own
@@ -393,12 +417,22 @@ static int tegra241_vintf_hw_init(struct tegra241_vintf *vintf, bool hyp_own)
tegra241_vintf_hw_deinit(vintf);

/* Configure and enable VINTF */
+ /*
+ * Note that HYP_OWN bit is wired to zero when running in guest kernel,
+ * whether enabling it here or not, as !HYP_OWN cmdq HWs only support a
+ * restricted set of supported commands.
+ */
regval = FIELD_PREP(VINTF_HYP_OWN, hyp_own);
writel(regval, REG_VINTF(vintf, CONFIG));

ret = vintf_write_config(vintf, regval | VINTF_EN);
if (ret)
return ret;
+ /*
+ * As being mentioned above, HYP_OWN bit is wired to zero for a guest
+ * kernel, so read it back from HW to ensure that reflects in hyp_own
+ */
+ vintf->hyp_own = !!(VINTF_HYP_OWN & readl(REG_VINTF(vintf, CONFIG)));

for (lidx = 0; lidx < vintf->cmdqv->num_lvcmdqs_per_vintf; lidx++) {
if (vintf->lvcmdqs && vintf->lvcmdqs[lidx]) {
--
2.43.0