linux-kernel - [PATCH 18/27] drm/amdkfd: add SPM support for SVM

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Message-Id: <20220210072828.2930359-19-hch@lst.de>
Date:   Thu, 10 Feb 2022 08:28:19 +0100
From:   Christoph Hellwig <hch@....de>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     Felix Kuehling <Felix.Kuehling@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Karol Herbst <kherbst@...hat.com>,
        Lyude Paul <lyude@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Alistair Popple <apopple@...dia.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        nvdimm@...ts.linux.dev, linux-mm@...ck.org,
        Alex Sierra <alex.sierra@....com>
Subject: [PATCH 18/27] drm/amdkfd: add SPM support for SVM

From: Alex Sierra <alex.sierra@....com>

When CPU is connected throug XGMI, it has coherent
access to VRAM resource. In this case that resource
is taken from a table in the device gmc aperture base.
This resource is used along with the device type, which could
be DEVICE_PRIVATE or DEVICE_COHERENT to create the device
page map region.

Signed-off-by: Alex Sierra <alex.sierra@....com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@....com>
Signed-off-by: Christoph Hellwig <hch@....de>
---
 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 28 ++++++++++++++----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index e27ca375876230..2c51f2ac3b46ac 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -933,7 +933,7 @@ int svm_migrate_init(struct amdgpu_device *adev)
 {
 	struct kfd_dev *kfddev = adev->kfd.dev;
 	struct dev_pagemap *pgmap;
-	struct resource *res;
+	struct resource *res = NULL;
 	unsigned long size;
 	void *r;
 
@@ -948,28 +948,34 @@ int svm_migrate_init(struct amdgpu_device *adev)
 	 * should remove reserved size
 	 */
 	size = ALIGN(adev->gmc.real_vram_size, 2ULL << 20);
-	res = devm_request_free_mem_region(adev->dev, &iomem_resource, size);
-	if (IS_ERR(res))
-		return -ENOMEM;
+	if (adev->gmc.xgmi.connected_to_cpu) {
+		pgmap->range.start = adev->gmc.aper_base;
+		pgmap->range.end = adev->gmc.aper_base + adev->gmc.aper_size - 1;
+		pgmap->type = MEMORY_DEVICE_COHERENT;
+	} else {
+		res = devm_request_free_mem_region(adev->dev, &iomem_resource, size);
+		if (IS_ERR(res))
+			return -ENOMEM;
+		pgmap->range.start = res->start;
+		pgmap->range.end = res->end;
+		pgmap->type = MEMORY_DEVICE_PRIVATE;
+	}
 
-	pgmap->type = MEMORY_DEVICE_PRIVATE;
 	pgmap->nr_range = 1;
-	pgmap->range.start = res->start;
-	pgmap->range.end = res->end;
 	pgmap->ops = &svm_migrate_pgmap_ops;
 	pgmap->owner = SVM_ADEV_PGMAP_OWNER(adev);
-	pgmap->flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
-
+	pgmap->flags = 0;
 	/* Device manager releases device-specific resources, memory region and
 	 * pgmap when driver disconnects from device.
 	 */
 	r = devm_memremap_pages(adev->dev, pgmap);
 	if (IS_ERR(r)) {
 		pr_err("failed to register HMM device memory\n");
-
 		/* Disable SVM support capability */
 		pgmap->type = 0;
-		devm_release_mem_region(adev->dev, res->start, resource_size(res));
+		if (pgmap->type == MEMORY_DEVICE_PRIVATE)
+			devm_release_mem_region(adev->dev, res->start,
+						res->end - res->start + 1);
 		return PTR_ERR(r);
 	}
 
-- 
2.30.2