Am 24.08.2018 um 01:05 schrieb Jiandi An:
On 08/23/2018 01:47 AM, Christian König wrote:Thanks for the suggestion and guidance. So you want me to register the callbacks something like virtio_gpu_ttm_populate() and virtio_gpu_ttm_unpopulate() in the virtio_gpu_bo_driver,Am 22.08.2018 um 22:57 schrieb Jiandi An:On 08/22/2018 02:09 PM, Christian König wrote:The path where the issue comes in is booting guest with AMD SEV enabled while using virtio-vga device.Am 22.08.2018 um 20:57 schrieb Jiandi An:NAK, the memory not only needs to be decrypted while CPU accessed but all the time.Framebuffer memory needs to be accessed decrypted. Ensure the memory encryption mask is not set for the ttm framebuffer mappings.ttm_page_alloc.c and ttm_page_alloc_dma.c should already take care of that while mapping the pages.Regards, Christian.The ttm->pages doesn't go through ttm_populate_and_map_pages().And that is the point where you need to jump in and fix the problem.When a driver implements the populate() and unpopulate() callbacks themselves it needs to take care of all that handling.
Yes, that is one possibility. The alternative is directly hack that into the ttm_tt_populate() and ttm_tt_unpopulate() functions.
and perform mapping by calling ttm_bo_kmap()? Then bring setting memory decrypted/encryped by calling set_memory_decrypted()/set_memory_encrypted() outside of ttm_bo_kmap(), do it within virtio_gpu_ttm_populate() and virtio_gpu_ttm_unpopulate() callbacks?
No, don't call ttm_bo_kmap() here. I think I now understand where we have a misunderstanding.
ttm_bo_kmap() just creates a vmap of the original pages to make them look linear to the kernel space.
What you need to do instead is to change the attributes of the original page mapping, not the copy in the vmap.
In other words you should call set_memory_decrypted() for each individually allocated page.
Then get rid of the separate call of virtio_gpu_vmap_fb() the virtio_gpu driver does?In the kernel path, the virtio_gpu driver calls virtio_gpu_alloc_object() and goes down to ttm to allocate pages in ttm_pool_populate(). Driver in guest then does virtio_gpu_vmap_fb() which goes down to ttm_bo_kmap_ttm() and does a vmap() for GVA to GPA for those pages. If SEV is enabled,decryption should be set in this GVA to GPA mapping.That assumption is what is incorrect here.TTM can't work with encrypted pages, so you need to set the pages as decrypted directly after calling ttm_pool_populate().And obviously set it to encrypted again before calling ttm_pool_unpopulate().Probably best if we add that to ttm_tt_populate()/ttm_tt_unpopulate().Here when you say ttm_tt_populate() and ttm_tt_unpopulate() you mean the virtio_gpu_ttm_populate() and virtio_gpu_ttm_unpopulate() that I register in virtio_gpu_bo_driver right?
Either as driver specific callbacks or directly in the fallback path of ttm_tt_populate() and ttm_tt_unpopulate().
Regards, Christian.
Regards, Christian.Guest then sends object attach command to hostvia virtio_gpu_object_attach() which stuffs the pages' physical addresses (guest physical address) in a scatter list and send them to host QEMU. Host QEMU maps those guest pages GPA to HPA and accessvia HVA while guest write stuff in those pages via GVA. virtio_gpu_alloc_object() virtio_gpu_object_create() sturct virtio_gpu_object bo kzalloc() ttm_bo_init() ... ttm_tt_create() bo->ttm = bdev->driver->ttm_tt_create() virtio_gpu_ttm_tt_create() ... ttm_tt_populate() ttm_pool_populate() ttm_get_pages(ttm->pages, ttm->num_pages) virtio_gpu_vmap_fb() virtio_gpu_object_kmap(obj, NULL) ttm_bo_kmap ttm_mem_io_reserve() ttm_bo_kmap_ttm() vmap()struct virtio_gpu_object bo->vmap = ttm_kmap_obj_virtual(&bo->kmap, &is_iomem);virtio_gpu_object_attach() <<== Sending attach backing command virtio_gpu_object_get_sg_table() if (bo->tbo.ttm->state == tt_unpopulated)virtio_gpu_object bo.ttm->bdev->driver->ttm_tt_populate(bo->tbo.ttm, &ctx);bo->pages = kmalloc(sizeof(struct sg_table), GFP_KERNEL);sg_alloc_table_from_pages(bo->tbo.ttm->pages) //Getfrom ttm->pages and put in sg__sg_alloc_table_from_pages()There is a separate userspace path for example when displace manager kicks in, virtio_gpu_alloc_object() followed by virtio_gpu_object_attach() are called through the ioctl virtio_gpu_resource_create_ioctl(). The mapping of the pages created in this page are handled in the do_page_fault() path in ttm_bo_vm_ops's ttm_bo_vm_fault() handler.do_page_fault() handle_mm_fault() __do_page_fault() ttm_bo_vm_fault() ttm_bo_reserve() __ttm_bo_reserve() ttm_mem_io_reserve_vm() ttm_mem_io_reserve() bdev->driver->io_mem_reserve() virtio_gpu_ttm_io_mem_reserve() mem->bus.is_iomem = false mem->mem_type == TTM_PL_TTI originally handled setting pages decrypted for the kernel path for GVA to GPA mapping in guest in virtio_gpu_vmap_fb() at the virtio_gpu driver layer. But for the user space path virtio_gpu_vmap_fb() is not called. Mapping is handled in the page_fault handler. So I moved itto the ttm layer.What layer do you recommend as more appropriate to handle setting memory decrypted for GVA to GPAmapping for thos ttm->pages? Thanks JiandiSigned-off-by: Jiandi An <jiandi.an@xxxxxxx> --- drivers/gpu/drm/ttm/ttm_bo_util.c | 12 +++++++++++- drivers/gpu/drm/ttm/ttm_bo_vm.c | 6 ++++-- 2 files changed, 15 insertions(+), 3 deletions(-)diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.cindex 046a6dda690a..b3f5d26f571e 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -29,6 +29,7 @@ * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com> */ +#include <asm/set_memory.h> #include <drm/ttm/ttm_bo_driver.h> #include <drm/ttm/ttm_placement.h> #include <drm/drm_vma_manager.h> @@ -639,7 +640,11 @@ int ttm_bo_kmap(struct ttm_buffer_object *bo, if (ret) return ret; if (!bo->mem.bus.is_iomem) { - return ttm_bo_kmap_ttm(bo, start_page, num_pages, map); + ret = ttm_bo_kmap_ttm(bo, start_page, num_pages, map); + if (!ret && sev_active()) + set_memory_decrypted((unsigned long) map->virtual, + num_pages); + return ret; } else { offset = start_page << PAGE_SHIFT; size = num_pages << PAGE_SHIFT; @@ -661,9 +666,14 @@ void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map) iounmap(map->virtual); break; case ttm_bo_map_vmap: + if (sev_active()) + set_memory_encrypted((unsigned long) map->virtual, + bo->num_pages); vunmap(map->virtual); break; case ttm_bo_map_kmap: + if (sev_active()) + set_memory_encrypted((unsigned long) map->virtual, 1); kunmap(map->page); break; case ttm_bo_map_premapped:diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.cindex 6fe91c1b692d..211d3549fd9f 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c@@ -249,10 +249,12 @@ static vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)* Speculatively prefault a number of pages. Only error on * first page. */ + + /* Mark framebuffer pages decrypted */ + cvma.vm_page_prot = pgprot_decrypted(cvma.vm_page_prot); + for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) { if (bo->mem.bus.is_iomem) { - /* Iomem should not be marked encrypted */ - cvma.vm_page_prot = pgprot_decrypted(cvma.vm_page_prot); pfn = ttm_bo_io_mem_pfn(bo, page_offset); } else { page = ttm->pages[page_offset];
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