[PATCH v13 10/48] arm64: RMI: Ensure that the RMM has GPT entries for memory

Steven Price
2026-03-18T15:55:02Z

The RMM may not be tracking all the memory of the system at boot. Create
the necessary tracking state and GPTs within the RMM so that all boot
memory can be delegated to the RMM as needed during runtime.

Note: support is currently missing for SROs which means that if the RMM
needs memory donating this will fail (and render CCA unusable in Linux).

Signed-off-by: Steven Price <steven.price@arm.com>
---
New patch for v13
---
arch/arm64/kvm/rmi.c | 89 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 89 insertions(+)

diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c
index 9590dff9a2c1..80aedc85e94a 100644
--- a/arch/arm64/kvm/rmi.c
+++ b/arch/arm64/kvm/rmi.c
@@ -4,6 +4,7 @@
*/

#include <linux/kvm_host.h>
+#include <linux/memblock.h>

#include <asm/kvm_pgtable.h>
#include <asm/rmi_cmds.h>
@@ -56,6 +57,18 @@ static int rmi_check_version(void)
return 0;
}

+/*
+ * These are the 'default' sizes when passing 0 as the tracking_region_size.
+ * TODO: Support other granule sizes
+ */
+#ifdef CONFIG_PAGE_SIZE_4KB
+#define RMM_GRANULE_TRACKING_SIZE SZ_1G
+#elif defined(CONFIG_PAGE_SIZE_16KB)
+#define RMM_GRANULE_TRACKING_SIZE SZ_32M
+#elif defined(CONFIG_PAGE_SIZE_64KB)
+#define RMM_GRANULE_TRACKING_SIZE SZ_512M
+#endif
+
static int rmi_configure(void)
{
struct rmm_config *config __free(free_page) = NULL;
@@ -95,6 +108,80 @@ static int rmi_configure(void)
return 0;
}

+static int rmi_verify_memory_tracking(phys_addr_t start, phys_addr_t end)
+{
+ start = ALIGN_DOWN(start, RMM_GRANULE_TRACKING_SIZE);
+ end = ALIGN(end, RMM_GRANULE_TRACKING_SIZE);
+
+ while (start < end) {
+ unsigned long ret, category, state;
+
+ ret = rmi_granule_tracking_get(start, &category, &state);
+ if (ret != RMI_SUCCESS ||
+ state != RMI_TRACKING_FINE ||
+ category != RMI_MEM_CATEGORY_CONVENTIONAL) {
+ /* TODO: Set granule tracking in this case */
+ kvm_err("Granule tracking for region isn't fine/conventional: %llx",
+ start);
+ return -ENODEV;
+ }
+ start += RMM_GRANULE_TRACKING_SIZE;
+ }
+
+ return 0;
+}
+
+static unsigned long rmi_l0gpt_size(void)
+{
+ return 1UL << (30 + FIELD_GET(RMI_FEATURE_REGISTER_1_L0GPTSZ,
+ rmm_feat_reg1));
+}
+
+static int rmi_create_gpts(phys_addr_t start, phys_addr_t end)
+{
+ unsigned long l0gpt_sz = rmi_l0gpt_size();
+
+ start = ALIGN_DOWN(start, l0gpt_sz);
+ end = ALIGN(end, l0gpt_sz);
+
+ while (start < end) {
+ int ret = rmi_gpt_l1_create(start);
+
+ if (ret && ret != RMI_ERROR_GPT) {
+ /*
+ * FIXME: Handle SRO so that memory can be donated for
+ * the tables.
+ */
+ kvm_err("GPT Level1 table missing for %llx\n", start);
+ return -ENOMEM;
+ }
+ start += l0gpt_sz;
+ }
+
+ return 0;
+}
+
+static int rmi_init_metadata(void)
+{
+ phys_addr_t start, end;
+ const struct memblock_region *r;
+
+ for_each_mem_region(r) {
+ int ret;
+
+ start = memblock_region_memory_base_pfn(r) << PAGE_SHIFT;
+ end = memblock_region_memory_end_pfn(r) << PAGE_SHIFT;
+ ret = rmi_verify_memory_tracking(start, end);
+ if (ret)
+ return ret;
+ ret = rmi_create_gpts(start, end);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
static int rmm_check_features(void)
{
if (kvm_lpa2_is_enabled() && !rmi_has_feature(RMI_FEATURE_REGISTER_0_LPA2)) {
@@ -120,6 +207,8 @@ void kvm_init_rmi(void)
return;
if (rmi_configure())
return;
+ if (rmi_init_metadata())
+ return;

/* Future patch will enable static branch kvm_rmi_is_available */
}
--
2.43.0