linux-kernel - [PATCH RFC] drm/amdgpu: Block userspace mapping of IO

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Message-Id: <20250416072825.3790-1-ujwal.kundur@gmail.com>
Date: Wed, 16 Apr 2025 12:58:26 +0530
From: Ujwal Kundur <ujwal.kundur@...il.com>
To: alexander.deucher@....com,
	christian.koenig@....com
Cc: airlied@...il.com,
	simona@...ll.ch,
	lijo.lazar@....com,
	sunil.khatri@....com,
	Hawking.Zhang@....com,
	Jun.Ma2@....com,
	Yunxiang.Li@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Ujwal Kundur <ujwal.kundur@...il.com>
Subject: [PATCH RFC] drm/amdgpu: Block userspace mapping of IO

This is a RFC patch for blocking userspace mapping of IO register(s)
before ioremap() calls are made. Out of the available IRQ sources, CRTC
seemed the most appropriate for this task, however I'm not quite sure
about that as well as the type, which I've set to 0.

If I understand correctly, we actually want to block certain ioctls from
userspace that can interfere with ioremap but I don't see a dedicated
source for that.

Signed-off-by: Ujwal Kundur <ujwal.kundur@...il.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index a30111d2c3ea..365af52af6e5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -47,6 +47,7 @@
 #include <linux/vga_switcheroo.h>
 #include <linux/efi.h>
 #include "amdgpu.h"
+#include "amdgpu_irq.h"
 #include "amdgpu_trace.h"
 #include "amdgpu_i2c.h"
 #include "atom.h"
@@ -4367,7 +4368,9 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	ratelimit_set_flags(&adev->throttling_logging_rs, RATELIMIT_MSG_ON_RELEASE);
 
 	/* Registers mapping */
-	/* TODO: block userspace mapping of io register */
+	/* Block userspace mapping of io register */
+	amdgpu_irq_put(adev, &adev->crtc_irq, 0);
+
 	if (adev->asic_type >= CHIP_BONAIRE) {
 		adev->rmmio_base = pci_resource_start(adev->pdev, 5);
 		adev->rmmio_size = pci_resource_len(adev->pdev, 5);
@@ -4380,6 +4383,9 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 		atomic_set(&adev->pm.pwr_state[i], POWER_STATE_UNKNOWN);
 
 	adev->rmmio = ioremap(adev->rmmio_base, adev->rmmio_size);
+
+	amdgpu_irq_get(adev, &adev->crtc_irq, 0);
+
 	if (!adev->rmmio)
 		return -ENOMEM;
 
-- 
2.20.1