Re: [PATCH v19 6/7] firmware: arm_rmm: Ensure the RMM has GPT entries for memory
From: Suzuki K Poulose
Date: Tue Sep 29 2026 - 18:25:23 EST
On 29/09/2026 23:17, Shanker Donthineni wrote:
Hi Suzuki,
On 9/24/2026 8:52 AM, Suzuki K Poulose wrote:
External email: Use caution opening links or attachments
From: Steven Price <steven.price@xxxxxxx>
The RMM maintains the state of all the granules in the system to make
sure that the host is abiding by the rules. This state can be maintained
at different granularity, per page (TRACKING_FINE) or per region
(TRACKING_COARSE or TRACKING_INTERMEDIATE). The region size depends on the
underlying "RMI_GRANULE_SIZE". For a "coarse"/"intermediate" region,
all pages in the region must be of the same state, this implies we need to
have "fine" tracking for DRAM, so that we can delegate individual pages.
For now we only support a statically carved out memory for tracking
granules for the "fine" regions. This can be extended in the future to
allow modifying the tracking granularity and remove the need for a
static allocation by the firmware.
Like the commit description says here ...
+/*
+ * Make sure the area is tracked by RMM at FINE granularity.
+ * We do not support changing the tracking yet.
+ */
+static int rmi_verify_memory_tracking(phys_addr_t start, phys_addr_t end)
+{
+ while (start < end) {
+ unsigned long ret, category, state, next;
+
+ ret = rmi_granule_tracking_get(start, end, &category, &state, &next);
+ if (ret != RMI_SUCCESS)
+ return -ENOMEM;
+
+ if (WARN_ON(next <= start))
+ return -ENXIO;
+
+ if (state != RMI_TRACKING_FINE ||
+ category != RMI_MEM_CATEGORY_CONVENTIONAL) {
+ /* TODO: Set granule tracking in this case */
+ pr_err("Granule tracking for region isn't fine/conventional: %llx-%lx\n",
+ start, next);
+ return -ENODEV;
This rejects any region the RMM does not already report as FINE,
but the initial tracking state is IMPLEMENTATION DEFINED, nothing
in DEN0137 Beta3 requires it to be FINE out of reset, and the full
RMI_TRACKING_* range is legal to observe here.
Agreed. This was a deliberate decision to keep this series simple.
Once we have a base support merged, we can add support for dynamic
tracking and GPTs.
Kind regards
Suzuki
On NVIDIA platforms it is not FINE, so this path fails and CCA cannot
be enabled at all. The TODO above is therefore load-bearing rather than
an optimisation: the driver has to promote the region with
RMI_GRANULE_TRACKING_SET and re-query, not bail out.
-Shanker
+ }
+ start = next;
+ }
+
+ return 0;
+}
+
+/*
+ * rmi_gpt_info - Query the GPT info for the given PAR.
+ * @start: Base of the physical address region
+ * @end: Top of the physical address region
+ * @out_top: Top of the physical address region for which
+ * the GPT @out_gpt_par_state is valid
+ * @out_gpt_par_state: State of the GPT covered by [start, out_top)
+ */
+static long rmi_gpt_info(unsigned long start, unsigned long end,
+ unsigned long *out_top,
+ unsigned long *out_gpt_par_state)
+{
+ struct arm_smccc_1_2_regs regs = {
+ SMC_RMI_GPT_INFO, start, end,
+ };
+
+ rmi_smccc_invoke(®s);
+ if (regs.a0 != RMI_SUCCESS)
+ return regs.a0;
+
+ if (out_top)
+ *out_top = regs.a1;
+ if (out_gpt_par_state)
+ *out_gpt_par_state = regs.a2;
+
+ return RMI_SUCCESS;
+}
+
+/*
+ * We do not support creating L1 GPTs yet. So, make sure that
+ * all the regions are managed by the firmware.
+ */
+static int rmi_verify_gpt_firmware_managed(phys_addr_t start, phys_addr_t end)
+{
+ unsigned long l0gpt_sz;
+ unsigned long next, par_state;
+
+ l0gpt_sz = 1UL << (30 + FIELD_GET(RMI_FEATURE_REGISTER_1_L0GPTSZ,
+ rmi_feat_reg(1)));
+ start = ALIGN_DOWN(start, l0gpt_sz);
+ end = ALIGN(end, l0gpt_sz);
+
+ while (start < end) {
+ long ret = rmi_gpt_info(start, end, &next, &par_state);
+
+ if (ret != RMI_SUCCESS)
+ return -ENOMEM;
+
+ if (WARN_ON(next <= start))
+ return -ENXIO;
+
+ if (par_state != RMI_GPT_PAR_PLAT) {
+ pr_err("GPT for the region is not managed by firmware %llx-%lx\n",
+ start, next);
+ return -ENOMEM;
+ }
+ start = next;
+ }
+
+ return 0;
+}
+
+static int rmi_prepare_memory(phys_addr_t start, phys_addr_t end)
+{
+ int ret;
+
+ if (start >= end)
+ return -EINVAL;
+
+ ret = rmi_verify_memory_tracking(start, end);
+ if (ret)
+ return ret;
+
+ return rmi_verify_gpt_firmware_managed(start, end);
+}
+
+static int rmi_init_metadata(void)
+{
+ phys_addr_t start, end;
+ struct memblock_region *r;
+
+ for_each_mem_region(r) {
+ int ret;
+
+ /* Firmware-reserved NOMAP regions are not usable system RAM */
+ if (memblock_is_nomap(r))
+ continue;
+
+ start = PAGE_ALIGN(r->base);
+ end = PAGE_ALIGN_DOWN(r->base + r->size);
+ /* Too small ? */
+ if (start >= end)
+ continue;
+
+ ret = rmi_prepare_memory(start, end);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int rmi_memory_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct memory_notify *arg = data;
+ phys_addr_t start, end;
+ int ret;
+
+ if (action != MEM_GOING_ONLINE)
+ return NOTIFY_DONE;
+
+ start = PFN_PHYS(arg->start_pfn);
+ end = PFN_PHYS(arg->start_pfn + arg->nr_pages);
+ ret = rmi_prepare_memory(start, end);
+
+ return notifier_from_errno(ret);
+}
+
+static struct notifier_block rmi_memory_nb = {
+ .notifier_call = rmi_memory_notifier,
+};
+
+bool is_rmi_available(void)
+{
+ return arm64_rmi_is_available;
+}
+EXPORT_SYMBOL_GPL(is_rmi_available);
+
+static int rmi_init_memory(void)
+{
+ int ret;
+
+ ret = rmi_init_metadata();
+ if (ret)
+ return ret;
+
+ return register_memory_notifier(&rmi_memory_nb);
+}
+
static int __init arm64_init_rmi(void)
{
int ret;
@@ -843,9 +1049,19 @@ static int __init arm64_init_rmi(void)
if (ret) {
pr_err("RMM activate failed (%d)\n", ret);
ret = ret < 0 ? ret : -ENXIO;
+ return ret;
}
- return ret;
+ ret = rmi_init_memory();
+ if (ret) {
+ /* Deactivate the RMM */
+ WARN_ON(rmi_sro_memxfer_cmd(sro, GFP_KERNEL, SMC_RMI_RMM_DEACTIVATE));
+ return ret;
+ }
+
+ arm64_rmi_is_available = true;
+ pr_info("RMI configured\n");
+ return 0;
}
/*
diff --git a/include/linux/arm-rmi-cmds.h b/include/linux/arm-rmi-cmds.h
index b03974fd8168c..5b177bb176326 100644
--- a/include/linux/arm-rmi-cmds.h
+++ b/include/linux/arm-rmi-cmds.h
@@ -70,6 +70,8 @@ static inline int rmi_undelegate_page(phys_addr_t phys)
return rmi_undelegate_range(phys, PAGE_SIZE);
}
+bool is_rmi_available(void);
+
long rmi_sro_memxfer_execute(struct rmi_sro_state *sro, gfp_t gfp);
void rmi_sro_free(struct rmi_sro_state *sro);
long rmi_sro_execute(struct arm_smccc_1_2_regs *regs);
--
2.43.0