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From:   <bchalios@amazon.es>
To:     <linux-kernel@vger.kernel.org>
CC:     <bchalios@amazon.es>, <tytso@mit.edu>, <Jason@zx2c4.com>,
        <dwmw@amazon.co.uk>, <graf@amazon.de>, <xmarcalx@amazon.co.uk>,
        <gregkh@linuxfoundation.org>
Subject: [PATCH 1/2] virt: vmgenid: add helper function to parse ADDR
Date:   Wed, 3 Aug 2022 17:21:26 +0200
Message-ID: <20220803152127.48281-2-bchalios@amazon.es>
In-Reply-To: <20220803152127.48281-1-bchalios@amazon.es>
References: <20220803152127.48281-1-bchalios@amazon.es>
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From: Babis Chalios <bchalios@amazon.es>

Add a helper function to parse the objects of the vmgenid device and use
it to parse the "ADDR" object and return the physical address of vmgenid
data. This prepares the code for adding support for an extra object
including the address of a vmgenid generation counter.

Signed-off-by: Babis Chalios <bchalios@amazon.es>
---
 drivers/virt/vmgenid.c | 50 ++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
index a1c467a0e..0cc2fe0f4 100644
--- a/drivers/virt/vmgenid.c
+++ b/drivers/virt/vmgenid.c
@@ -21,24 +21,20 @@ struct vmgenid_state {
 	u8 this_id[VMGENID_SIZE];
 };
 
-static int vmgenid_add(struct acpi_device *device)
+static int parse_vmgenid_address(struct acpi_device *device, acpi_string object_name,
+		phys_addr_t *phys_addr)
 {
 	struct acpi_buffer parsed = { ACPI_ALLOCATE_BUFFER };
-	struct vmgenid_state *state;
-	union acpi_object *obj;
-	phys_addr_t phys_addr;
 	acpi_status status;
+	union acpi_object *obj;
 	int ret = 0;
 
-	state = devm_kmalloc(&device->dev, sizeof(*state), GFP_KERNEL);
-	if (!state)
-		return -ENOMEM;
-
-	status = acpi_evaluate_object(device->handle, "ADDR", NULL, &parsed);
+	status = acpi_evaluate_object(device->handle, object_name, NULL, &parsed);
 	if (ACPI_FAILURE(status)) {
-		ACPI_EXCEPTION((AE_INFO, status, "Evaluating ADDR"));
+		ACPI_EXCEPTION((AE_INFO, status, "Evaluating vmgenid object"));
 		return -ENODEV;
 	}
+
 	obj = parsed.pointer;
 	if (!obj || obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 2 ||
 	    obj->package.elements[0].type != ACPI_TYPE_INTEGER ||
@@ -47,22 +43,38 @@ static int vmgenid_add(struct acpi_device *device)
 		goto out;
 	}
 
-	phys_addr = (obj->package.elements[0].integer.value << 0) |
-		    (obj->package.elements[1].integer.value << 32);
+	*phys_addr = (obj->package.elements[0].integer.value << 0) |
+		     (obj->package.elements[1].integer.value << 32);
+
+out:
+	ACPI_FREE(parsed.pointer);
+	return ret;
+}
+
+static int vmgenid_add(struct acpi_device *device)
+{
+	struct vmgenid_state *state;
+	phys_addr_t phys_addr;
+	int ret;
+
+	state = devm_kmalloc(&device->dev, sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	ret = parse_vmgenid_address(device, "ADDR", &phys_addr);
+	if (ret)
+		return ret;
+
 	state->next_id = devm_memremap(&device->dev, phys_addr, VMGENID_SIZE, MEMREMAP_WB);
-	if (IS_ERR(state->next_id)) {
-		ret = PTR_ERR(state->next_id);
-		goto out;
-	}
+	if (IS_ERR(state->next_id))
+		return PTR_ERR(state->next_id);
 
 	memcpy(state->this_id, state->next_id, sizeof(state->this_id));
 	add_device_randomness(state->this_id, sizeof(state->this_id));
 
 	device->driver_data = state;
 
-out:
-	ACPI_FREE(parsed.pointer);
-	return ret;
+	return 0;
 }
 
 static void vmgenid_notify(struct acpi_device *device, u32 event)
-- 
2.32.1 (Apple Git-133)

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