RMM v2.0 brings the ability to set the RMM's granule size. Check the
feature registers and configure the RMM so that it matches the host's
page size. This means that operations can be done with a granularity
equal to PAGE_SIZE.

Signed-off-by: Steven Price <steven.price@arm.com>
---
Changes since v14:
 * Move the implementation into drivers/firmware/arm_rmm.
Changes since v13:
 * Moved out of KVM.
---
 drivers/firmware/arm_rmm/rmi.c | 43 ++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/drivers/firmware/arm_rmm/rmi.c b/drivers/firmware/arm_rmm/rmi.c
index c4850976544f..e7ab4a7df3ca 100644
--- a/drivers/firmware/arm_rmm/rmi.c
+++ b/drivers/firmware/arm_rmm/rmi.c
@@ -76,6 +76,45 @@ static int rmi_read_features(void)
 	return 0;
 }
 
+static int rmi_configure(void)
+{
+	unsigned long ret;
+	struct rmm_config *config __free(free_page) = (struct rmm_config *)get_zeroed_page(GFP_KERNEL);
+
+	if (!config)
+		return -ENOMEM;
+
+	switch (PAGE_SIZE) {
+	case SZ_4K:
+		config->rmi_granule_size = RMI_GRANULE_SIZE_4KB;
+		break;
+	case SZ_16K:
+		config->rmi_granule_size = RMI_GRANULE_SIZE_16KB;
+		break;
+	case SZ_64K:
+		config->rmi_granule_size = RMI_GRANULE_SIZE_64KB;
+		break;
+	default:
+		BUILD_BUG();
+	}
+
+	/*
+	 * For now we set the tracking_region_size to 0 which is the only option
+	 * for 4KB PAGE_SIZE (1GB for 4KB PAGE_SIZE, 32MB/512MB for 16KB/64KB).
+	 * TODO: Support other tracking sizes via Kconfig option for other
+	 * PAGE_SIZES
+	 */
+	config->tracking_region_size = 0;
+
+	ret = rmi_rmm_config_set(virt_to_phys(config));
+	if (ret) {
+		pr_err("RMM config set failed\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int __init arm64_init_rmi(void)
 {
 	int ret;
@@ -89,6 +128,10 @@ static int __init arm64_init_rmi(void)
 	if (ret)
 		return ret;
 
+	ret = rmi_configure();
+	if (ret)
+		return ret;
+
 	return 0;
 }
 
-- 
2.43.0