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Mon, 21 Sep 2026 06:37:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789972642; bh=fUCvSD545AGqyJgwYc/GicxI6hMF/t9YAHwv4jFcQak=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ItCAWN/bZKXBVisaCNeR/Zme4Bhaf0Rs8NXllfTFEHHwczMFALk0glxv5UtwQ2E1M A8qyeQOutrpDF0GB73be/Dhp7UyA76pr93qyXCp/SBgZlJv/us4v9DB8544n2XS0LO ZmWn9ULvzsnJeFZSk1zQIKMZHULsZm5+e33H56EKAvDfqjypjXEl/2I5CUNPqTuhyp HsqgaPygQtGAqNarWWmiPfWWkx7rgJDdc80k6kWbQ6xkbHO9IRuLGCTv9wtfUK4+vT TzOFDt8Xlr8T/WTX3YWtL/0YYcr0Rv2B1mevPDJnI55O5NaYEPvy5tlnh6c02ULEjb PLdVf4MFo0IFg== From: "Aneesh Kumar K.V (Arm)" To: iommu@lists.linux.dev, linux-kernel@vger.kernel.org Cc: "Aneesh Kumar K.V (Arm)" , Robin Murphy , Marek Szyprowski , Will Deacon , Marc Zyngier , Steven Price , Suzuki K Poulose , Catalin Marinas , Jiri Pirko , Jason Gunthorpe , Mostafa Saleh , Petr Tesarik , Alexey Kardashevskiy , Dan Williams , Xu Yilun , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Russell King , Huacai Chen , Thomas Bogendoerfer , Jiaxun Yang , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, x86@kernel.org Subject: [PATCH v5 2/6] dma: swiotlb: Track whether the pool size was explicitly set Date: Mon, 21 Sep 2026 12:06:24 +0530 Message-ID: <20260921063628.362078-3-aneesh.kumar@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260921063628.362078-1-aneesh.kumar@kernel.org> References: <20260921063628.362078-1-aneesh.kumar@kernel.org> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit swiotlb_adjust_size() must not override a pool size supplied through the swiotlb= command-line parameter. Currently, it determines whether a size was supplied by comparing default_nslabs with IO_TLB_DEFAULT_SIZE. This fails when the user explicitly requests the compiled-in default size, allowing the request to be overwritten by automatic pool sizing. Record whether swiotlb= supplied a numeric size and add swiotlb_default_size_changed() to query that state. Signed-off-by: Aneesh Kumar K.V (Arm) --- kernel/dma/swiotlb.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index aa19e81ae544..8f86deb25be2 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -107,6 +107,7 @@ static struct io_tlb_mem io_tlb_default_mem; static unsigned long default_nslabs = IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT; static unsigned long default_nareas; +static bool swiotlb_size_set __initdata; /** * struct io_tlb_area - IO TLB memory area descriptor @@ -269,6 +270,7 @@ setup_io_tlb_npages(char *str) /* avoid tail segment of size < IO_TLB_SEGSIZE */ default_nslabs = ALIGN(simple_strtoul(str, &str, 0), IO_TLB_SEGSIZE); + swiotlb_size_set = true; } if (*str == ',') ++str; @@ -304,6 +306,11 @@ unsigned long swiotlb_size_or_default(void) return default_nslabs << IO_TLB_SHIFT; } +static bool __init swiotlb_default_size_changed(void) +{ + return swiotlb_size_set; +} + void __init swiotlb_adjust_size(unsigned long size) { /* @@ -311,7 +318,7 @@ void __init swiotlb_adjust_size(unsigned long size) * architectures such as those supporting memory encryption to * adjust/expand SWIOTLB size for their use. */ - if (default_nslabs != IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT) + if (swiotlb_default_size_changed()) return; default_nslabs = swiotlb_aligned_nslabs(size); -- 2.43.0