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[79.49.199.193]) by smtp.gmail.com with ESMTPSA id kz11-20020a17090777cb00b0072af18329c4sm1968127ejc.225.2022.07.06.12.51.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Jul 2022 12:51:33 -0700 (PDT) From: "Andrea Parri (Microsoft)" To: Christoph Hellwig , Marek Szyprowski , Robin Murphy , KY Srinivasan , Haiyang Zhang , Stephen Hemminger , Wei Liu , Dexuan Cui , Michael Kelley , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Peter Anvin Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, iommu@lists.linux.dev, linux-hyperv@vger.kernel.org, x86@kernel.org, "Andrea Parri (Microsoft)" Subject: [RFC PATCH 2/2] dma-direct: Fix dma_direct_{alloc,free}() for Hyperv-V IVMs Date: Wed, 6 Jul 2022 21:50:27 +0200 Message-Id: <20220706195027.76026-3-parri.andrea@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220706195027.76026-1-parri.andrea@gmail.com> References: <20220706195027.76026-1-parri.andrea@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In Hyper-V AMD SEV-SNP Isolated VMs, the virtual address returned by dma_direct_alloc() must map above dma_unencrypted_base because the memory is shared with the hardware device and must not be encrypted. Modify dma_direct_alloc() to do the necessary remapping. In dma_direct_free(), use the (unmodified) DMA address to derive the original virtual address and re-encrypt the pages. Suggested-by: Michael Kelley Co-developed-by: Dexuan Cui Signed-off-by: Dexuan Cui Signed-off-by: Andrea Parri (Microsoft) --- kernel/dma/direct.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 06b2b901e37a3..c4ce277687a49 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -13,6 +13,7 @@ #include #include #include +#include /* for memremap() */ #include "direct.h" /* @@ -305,6 +306,21 @@ void *dma_direct_alloc(struct device *dev, size_t size, ret = page_address(page); if (dma_set_decrypted(dev, ret, size)) goto out_free_pages; +#ifdef CONFIG_HAS_IOMEM + /* + * Remap the pages in the unencrypted physical address space + * when dma_unencrypted_base is set (e.g., for Hyper-V AMD + * SEV-SNP isolated guests). + */ + if (dma_unencrypted_base) { + phys_addr_t ret_pa = virt_to_phys(ret); + + ret_pa += dma_unencrypted_base; + ret = memremap(ret_pa, size, MEMREMAP_WB); + if (!ret) + goto out_encrypt_pages; + } +#endif } memset(ret, 0, size); @@ -360,11 +376,23 @@ void dma_direct_free(struct device *dev, size_t size, dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size))) return; - if (is_vmalloc_addr(cpu_addr)) { + /* + * If dma_unencrypted_base is set, the virtual address returned by + * dma_direct_alloc() is in the vmalloc address range. + */ + if (!dma_unencrypted_base && is_vmalloc_addr(cpu_addr)) { vunmap(cpu_addr); } else { if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED)) arch_dma_clear_uncached(cpu_addr, size); +#ifdef CONFIG_HAS_IOMEM + if (dma_unencrypted_base) { + memunmap(cpu_addr); + /* re-encrypt the pages using the original address */ + cpu_addr = page_address(pfn_to_page(PHYS_PFN( + dma_to_phys(dev, dma_addr)))); + } +#endif if (dma_set_encrypted(dev, cpu_addr, size)) return; } -- 2.25.1