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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: nfIdEuym7Wenp2+9cc5EeRC/jNBA6XrfJq/0+bW8jqs/aefNsVbvF0PJ0v8kTidGIMYRqCZxFEVReDqundlLcAfgcpAaxpI3pTsCkG626YSEn2MvmF4GSeXEbB2aoZh1vcHxxkTu0S1vsH1aEwL+CSzUPONUHvpS2duaYdioMjicTKKm9xwvEDkVVzg9UznZ7VETyGhzEm5BR4zfuk9MKNRbClYHT4TpZPwT/g+GwQI7GwG/kOg+EaukrTSaSW6VnV+kqnkLIIkT60ZHngZteNyo8It5foXMStF7sQ97kDUso3INzfWedavktkK+ruphw+6C4CflOvnzVhPXKmwLwd2HJg9j3b7os+8moT8V4pj/GB54CK9fZJqCsndn0EKulDjzQCFPjgVcaPaKR5oHwMIvOnad/uJoRl/pScf1xv8c6lX5lV0bxWda2d1aEDpt X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Mar 2026 13:21:49.9192 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 176f80b0-23fb-4e2b-9046-08de7ea7fcdd X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: DU6PEPF00009529.eurprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: FRZPR08MB11098 On 10/03/2026 13:08, Catalin Marinas wrote: > On Thu, Mar 05, 2026 at 05:03:35PM +0000, Mostafa Saleh wrote: >> As restricted dma pools are always decrypted, in swiotlb.c it uses >> phys_to_dma_unencrypted() for address conversion. >> >> However, in DMA-direct, calls to phys_to_dma_direct() with >> force_dma_unencrypted() returning false, will fallback to >> phys_to_dma() which is inconsistent for memory allocated from >> restricted dma pools. >> >> Signed-off-by: Mostafa Saleh >> --- >> kernel/dma/direct.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c >> index 27d804f0473f..1a402bb956d9 100644 >> --- a/kernel/dma/direct.c >> +++ b/kernel/dma/direct.c >> @@ -26,7 +26,7 @@ u64 zone_dma_limit __ro_after_init = DMA_BIT_MASK(24); >> static inline dma_addr_t phys_to_dma_direct(struct device *dev, >> phys_addr_t phys) >> { >> - if (force_dma_unencrypted(dev)) >> + if (force_dma_unencrypted(dev) || is_swiotlb_for_alloc(dev)) >> return phys_to_dma_unencrypted(dev, phys); >> return phys_to_dma(dev, phys); >> } > > I couldn't fully get my head around the DMA API but I think all the > pools and bounce buffers are decrypted and protected guests (or realms > for Arm CCA) should always return true for force_dma_unencrypted(). If > that's the case, the above change wouldn't be necessary. I can see that > arm64 only does this for CCA and not pKVM guests. That is correct. Why would the force_dma_unencrypted() return false for a device ? As far as I can see, all CC guests are treating all devices as "untrusted" for now (and there is a series available that is adding support for "trusted devices [0]). > > Device assignment is another story that requires reworking those DMA > pools to support encrypted buffers. > [0] https://lkml.kernel.org/r/20260303000207.1836586-1-dan.j.williams@intel.com Suzuki