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Shutemov" To: "Lendacky, Thomas" Cc: "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , Christoph Hellwig , Marek Szyprowski , Robin Murphy , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Lianbo Jiang Subject: Re: [PATCH] dma-direct: Force unencrypted DMA under SME for certain DMA masks Message-ID: <20190724155530.hlingpcirjcf2ljg@box> References: <10b83d9ff31bca88e94da2ff34e30619eb396078.1562785123.git.thomas.lendacky@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <10b83d9ff31bca88e94da2ff34e30619eb396078.1562785123.git.thomas.lendacky@amd.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 10, 2019 at 07:01:19PM +0000, Lendacky, Thomas wrote: > @@ -351,6 +355,32 @@ bool sev_active(void) > } > EXPORT_SYMBOL(sev_active); > > +/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */ > +bool force_dma_unencrypted(struct device *dev) > +{ > + /* > + * For SEV, all DMA must be to unencrypted addresses. > + */ > + if (sev_active()) > + return true; > + > + /* > + * For SME, all DMA must be to unencrypted addresses if the > + * device does not support DMA to addresses that include the > + * encryption mask. > + */ > + if (sme_active()) { > + u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask)); > + u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask, > + dev->bus_dma_mask); > + > + if (dma_dev_mask <= dma_enc_mask) > + return true; Hm. What is wrong with the dev mask being equal to enc mask? IIUC, it means that device mask is wide enough to cover encryption bit, doesn't it? > + } > + > + return false; > +} -- Kirill A. Shutemov