From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D046E410D19 for ; Fri, 15 May 2026 09:40:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778838023; cv=none; b=AYPAtqj++tChSHSblqYIIoXmRcU+1oNnBMC7N2yu/Om1iceU0adg1damaAOzmZUdqE2X9eyf73U/fvPtNIecIZFTdstOxslmiVZcdVcvNpgxFJ2CTX8UXbSt637IozX3NGb8Lgp3QiTSRFg1seWzXxFm4YcsVVWDZ4GUt0Q6ysA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778838023; c=relaxed/simple; bh=upN5BjZU0ZFxJqHuEdTcT80edfTVaf1cATCLPEvpHDE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=T5/7/SkOpeJmn50+2X4e3o9tSuVI/l9bbs5dJ4+2VrRhK3ZWxPHgKbXJ7OUyGgEJUlpp1EcWPhQNMHGN3OX/BKBeFIYXe1oO/PUmErsYYJQYDg0OI3ljwy+SFDcoxG2MAruSnMe+c7qsW9lnfnPN2sK5vQzpg7ZRdYOME8Z2xCo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dl/Zr9oI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dl/Zr9oI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1258C2BCB0; Fri, 15 May 2026 09:40:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778838023; bh=upN5BjZU0ZFxJqHuEdTcT80edfTVaf1cATCLPEvpHDE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dl/Zr9oIDEeC3TCM2/PwvfC+qNDD/WEGZNb9vzTD4bfmj+xRX+8m6VTOb2tVizliP YrO8XlLAx1JWdnrYRU3DAdpwJ2+s4nosWnQUenY0fgI5q/NYDkSw68DUWd9GdcNCqd XB3xsgMO7P2+cUF3MSIU3IzdzwAT1gT9vh8YEcEtfbAyeGKBGCvUf7W3y5AW/yyfZ7 pvACbTzCzDQUQPEG4BNTHRFzKPlmpmHbTuZqNlUc6fHaHlpl60dtrQUXCbCBiOVmMh uQLHa1OFrezIbhmhu2OtNZMIAorS1sW5UBzlsUAQWhmwEIJWcdgLR2fxcyyvtVjh3F cSwEJPvN6hzHQ== Date: Fri, 15 May 2026 10:40:20 +0100 From: Sudeep Holla To: Jamie Nguyen Cc: "linux-arm-kernel@lists.infradead.org" , Sudeep Holla , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] firmware: arm_ffa: honor descriptor size in PARTITION_INFO_GET_REGS Message-ID: <20260515-quixotic-active-dragon-2ee2c6@sudeepholla> References: <20260513032800.68807-1-jamien@nvidia.com> <20260514-generous-undetectable-mastiff-cc43d3@sudeepholla> <27E42CCD-8518-4802-B549-A79B94B5658A@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <27E42CCD-8518-4802-B549-A79B94B5658A@nvidia.com> On Thu, May 14, 2026 at 05:37:41PM +0000, Jamie Nguyen wrote: > > > > On May 14, 2026, at 2:31 AM, Sudeep Holla wrote: > > > > On Tue, May 12, 2026 at 08:28:00PM -0700, Jamie Nguyen wrote: > >> __ffa_partition_info_get_regs() walks the response with a hardcoded > >> 24-byte stride (regs += 3) even though the SPMC tells us the actual > >> per-descriptor size via PARTITION_INFO_SZ in x2[63:48]. The size is > >> read into buf_sz and then thrown away. > >> > >> That works while every SPMC returns the FF-A v1.1 layout, but it falls > >> apart against a v1.3 SPMC returning the 48-byte descriptor. The loop > >> strides over half a descriptor at a time and ends up parsing every > >> other entry from a slice of two adjacent ones. > >> > >> The FF-A spec (v1.2, section 18.5) says that the producer should > >> report the descriptor size, and the consumer is supposed to stride by > >> that size and ignore any trailing fields it doesn't understand. The > >> non-REGS path (__ffa_partition_info_get) does this already, and the > >> REGS path should match. > >> > >> Use buf_sz for the stride, and bail out with -EPROTO if the SPMC > >> reports something we can't safely walk. > >> > >> Fixes: 7bc0f589c81d ("firmware: arm_ffa: Fix big-endian support in __ffa_partition_info_regs_get()") > >> Signed-off-by: Jamie Nguyen > >> --- > >> drivers/firmware/arm_ffa/driver.c | 35 ++++++++++++++++++++++++++++--- > >> 1 file changed, 32 insertions(+), 3 deletions(-) > >> > >> diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c > >> index c72ee4756585..b712e8a03dab 100644 > >> --- a/drivers/firmware/arm_ffa/driver.c > >> +++ b/drivers/firmware/arm_ffa/driver.c > >> @@ -321,6 +321,22 @@ __ffa_partition_info_get(u32 uuid0, u32 uuid1, u32 uuid2, u32 uuid3, > >> #define PART_INFO_ID(x) ((u16)(FIELD_GET(PART_INFO_ID_MASK, (x)))) > >> #define PART_INFO_EXEC_CXT(x) ((u16)(FIELD_GET(PART_INFO_EXEC_CXT_MASK, (x)))) > >> #define PART_INFO_PROPERTIES(x) ((u32)(FIELD_GET(PART_INFO_PROPS_MASK, (x)))) > >> + > >> +/* > >> + * FF-A v1.2 section 13.9 Table 13.40: registers x3..x17 carry the partition > >> + * descriptors, i.e. 15 u64 of payload per FFA_PARTITION_INFO_GET_REGS call. > >> + */ > >> +#define FFA_PART_INFO_REGS_PAYLOAD_U64 15 > >> + > >> +/* > >> + * FF-A v1.1 partition information descriptor (FF-A v1.2 section 6.2.1 > >> + * Table 6.1): id (2) + exec_ctxt (2) + properties (4) + UUID (16) = 24 > >> + * bytes. This is the minimum size the SPMC must report; the kernel reads > >> + * exactly these fields and ignores any trailing ones per the forward- > >> + * compatibility rules in FF-A v1.2 section 18.5. > >> + */ > > > > I can't see any such details is the above mention version and section. > > Can you confirm you are looking at [1] ? > > Yes, I am looking at [1]. The size field and the rule are in two > different places: > > - Section 13.9 Table 13.40, page 188: > x2 Bits[63:48] = "Size in bytes of each partition information > entry descriptor." > (read into buf_sz today and discarded) > Sorry my bad, I was looking at Section 18 and was confused a bit. > - Section 18.5 page 264 rule 4: > "A consumer of this data structure uses the size corresponding > to the Framework version it implements to consume only fields > defined in its version. Additional fields in the producer's > version of this data structure are safely ignored enabling > forward compatibility." > Now makes sense, was just looking at this w/o reading Section 13.9 > If you agree, I'll rebase against linux-next and send a v2. > Yes please. Thanks for your patience. -- Regards, Sudeep