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Tue, 09 Jun 2026 06:44:36 -0700 (PDT) Received: from mordecai ([62.77.90.70]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4601f360bd6sm66805957f8f.36.2026.06.09.06.44.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jun 2026 06:44:36 -0700 (PDT) Date: Tue, 9 Jun 2026 15:44:34 +0200 From: Petr Tesarik To: "Aneesh Kumar K.V (Arm)" Cc: iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, Robin Murphy , Marek Szyprowski , Will Deacon , Marc Zyngier , Steven Price , Suzuki K Poulose , Catalin Marinas , Jiri Pirko , Jason Gunthorpe , Mostafa Saleh , Alexey Kardashevskiy , Dan Williams , Xu Yilun , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , x86@kernel.org Subject: Re: [PATCH v6 20/20] swiotlb: remove unused SWIOTLB_FORCE flag Message-ID: <20260609154434.13dba7b9@mordecai> In-Reply-To: <20260604083959.1265923-21-aneesh.kumar@kernel.org> References: <20260604083959.1265923-1-aneesh.kumar@kernel.org> <20260604083959.1265923-21-aneesh.kumar@kernel.org> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260609_064438_980060_1A3A2DD8 X-CRM114-Status: GOOD ( 18.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 4 Jun 2026 14:09:59 +0530 "Aneesh Kumar K.V (Arm)" wrote: > SWIOTLB_FORCE has no remaining in-tree users. Forced bouncing is now > controlled through the swiotlb=force command line option via > swiotlb_force_bounce. > > Remove the unused flag and simplify the force_bounce initialization. > > Signed-off-by: Aneesh Kumar K.V (Arm) > --- > include/linux/swiotlb.h | 1 - > kernel/dma/swiotlb.c | 3 +-- > 2 files changed, 1 insertion(+), 3 deletions(-) > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > index 526f82e9da45..af88ca7182f4 100644 > --- a/include/linux/swiotlb.h > +++ b/include/linux/swiotlb.h > @@ -15,7 +15,6 @@ struct page; > struct scatterlist; > > #define SWIOTLB_VERBOSE (1 << 0) /* verbose initialization */ > -#define SWIOTLB_FORCE (1 << 1) /* force bounce buffering */ > #define SWIOTLB_ANY (1 << 2) /* allow any memory for the buffer */ These constants are kernel-internal, so let's not leave a hole in the bitmask... I mean, what about changing SWIOTLB_ANY to (1 << 1) after you remove SWIOTLB_FORCE? Other than that, LGTM. I consider this whole series a big step towards saner handling of encrypted/decrypted memory for DMA buffers. Thank you for your effort! Petr T > > /* > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index e4bd8c9eaeda..81cc4928e949 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -400,8 +400,7 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags, > if (swiotlb_force_disable) > return; > > - io_tlb_default_mem.force_bounce = > - swiotlb_force_bounce || (flags & SWIOTLB_FORCE); > + io_tlb_default_mem.force_bounce = swiotlb_force_bounce; > > #ifdef CONFIG_SWIOTLB_DYNAMIC > if (!remap)