From 0df02d448aa677ff20a8f5004a881cae48dd885e Mon Sep 17 00:00:00 2001
From: Elliot Berman <elliot.berman@oss.qualcomm.com>
Date: Fri, 7 Feb 2025 13:43:52 -0800
Subject: [PATCH] ANDROID: virt: gunyah: Probe for the info_area page

The Gunyah info_area page contains a series of descriptors of
"information". Probe the info_area page during probe and expose a
function to fetch information by its identifier.

Bug: 395833312
Change-Id: I380fa59259f487f1ca9b48c12eb07957603ea099
Signed-off-by: Elliot Berman <elliot.berman@oss.qualcomm.com>
---
 drivers/virt/gunyah/gunyah.c | 48 ++++++++++++++++++++++++++++++++++++
 include/linux/gunyah.h       | 12 +++++++++
 2 files changed, 60 insertions(+)

diff --git a/drivers/virt/gunyah/gunyah.c b/drivers/virt/gunyah/gunyah.c
index ef8a85f27590..7a6669a5675c 100644
--- a/drivers/virt/gunyah/gunyah.c
+++ b/drivers/virt/gunyah/gunyah.c
@@ -8,9 +8,45 @@
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 
+struct gunyah_info_desc {
+	__le16 id;
+	__le16 owner;
+	__le32 size;
+	__le32 offset;
+#define INFO_DESC_VALID		BIT(31)
+	__le32 flags;
+};
+
+static void *info_area;
+
+void *gunyah_get_info(u16 owner, u16 id, size_t *size)
+{
+	struct gunyah_info_desc *desc = info_area;
+	__le16 le_owner = cpu_to_le16(owner);
+	__le16 le_id = cpu_to_le16(id);
+
+	if (!desc)
+		return ERR_PTR(-ENOENT);
+
+	for (desc = info_area; le32_to_cpu(desc->offset); desc++) {
+		if (!(le32_to_cpu(desc->flags) & INFO_DESC_VALID))
+			continue;
+		mb();
+		if (le_owner == desc->owner && le_id == desc->id) {
+			if (size)
+				*size = le32_to_cpu(desc->size);
+			return info_area + le32_to_cpu(desc->offset);
+		}
+	}
+	return ERR_PTR(-ENOENT);
+}
+EXPORT_SYMBOL_GPL(gunyah_get_info);
+
 static int gunyah_probe(struct platform_device *pdev)
 {
 	struct gunyah_hypercall_hyp_identify_resp gunyah_api;
+	unsigned long info_ipa, info_size;
+	enum gunyah_error gh_error;
 
 	if (!arch_is_gunyah_guest())
 		return -ENODEV;
@@ -28,6 +64,18 @@ static int gunyah_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
+	gh_error = gunyah_hypercall_addrspace_find_info_area(&info_ipa, &info_size);
+	/* ignore errors for compatability with gh without info_area support */
+	if (gh_error != GUNYAH_ERROR_OK)
+		goto out;
+
+	info_area = memremap(info_ipa, info_size, MEMREMAP_WB);
+	if (!info_area) {
+		pr_err("Failed to map addrspace info area\n");
+		return -ENOMEM;
+	}
+
+out:
 	return devm_of_platform_populate(&pdev->dev);
 }
 
diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
index cc16803536e4..d6b1023e7d10 100644
--- a/include/linux/gunyah.h
+++ b/include/linux/gunyah.h
@@ -363,6 +363,18 @@ enum gunyah_api_feature {
 
 bool arch_is_gunyah_guest(void);
 
+enum gunyah_info_owner {
+	/* clang-format off */
+	GUNYAH_INFO_OWNER_INVALID	= 0,
+	GUNYAH_INFO_OWNER_HYP		= 1,
+	GUNYAH_INFO_OWNER_ROOTVM	= 2,
+	GUNYAH_INFO_OWNER_RM		= 3,
+	GUNYAH_INFO_OWNER_QCRM		= 16,
+	/* clang-format on */
+};
+
+void *gunyah_get_info(u16 owner, u16 id, size_t *size);
+
 #define GUNYAH_API_V1 1
 
 /* Other bits reserved for future use and will be zero */