From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B4C481A5B8D; Thu, 14 Aug 2025 15:28:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755185307; cv=none; b=HCCIn/1ESqPLKZt94D/sid5J16cVZNfrNP0l7WeaEAI1eLw+uQ1VyXXS+P8M9m0Z9QeqVYc75XqPPXnjTdEtvHGkVh3CNRj9q0p8ZYToke4uMeEsm0+P0QZNHAta8V3+BktYudBy7AWJPv9ljjvLUF1bqTRXeTTuYDj6PyIrSSE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755185307; c=relaxed/simple; bh=OtX8NQC4WyCIC6HX5tnUsUk0WKM0GZbwEuVcQ1HlxAE=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=rARQDOOY5XIwz4kLN5ZAW6qonb1b1FAv7FLoLGvaF+RqhMWTsy7xorS2djJRfjNCGJ1cZ8qBRDilDp/Dc+hy4ZaanZCtXcGbqfuKJRevWm01liDgHxa+caxHhetQYWoGdmsR7oj1WG0NTnBtlO4j+fNmluQIAUeYEQFWkTxzKZo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A36441691; Thu, 14 Aug 2025 08:28:16 -0700 (PDT) Received: from [10.1.196.50] (e121345-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7DDC63F5A1; Thu, 14 Aug 2025 08:28:23 -0700 (PDT) Message-ID: <6065d82b-0a07-4f82-8b4e-9c00374d2f71@arm.com> Date: Thu, 14 Aug 2025 16:28:17 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] iommu: Fix virtio-iommu probing To: eric.auger@redhat.com, eric.auger.pro@gmail.com, rafael@kernel.org, bhelgaas@google.com, jgg@ziepe.ca, lpieralisi@kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, lenb@kernel.org, jean-philippe@linaro.org, jsnitsel@redhat.com References: <20250814141758.2140641-1-eric.auger@redhat.com> <3fdbd23d-cd65-453b-aa8d-78f9ed1bc4c4@redhat.com> From: Robin Murphy Content-Language: en-GB In-Reply-To: <3fdbd23d-cd65-453b-aa8d-78f9ed1bc4c4@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 14/08/2025 4:19 pm, Eric Auger wrote: > Hi Robin > > On 8/14/25 4:53 PM, Robin Murphy wrote: >> On 14/08/2025 3:17 pm, Eric Auger wrote: >>> Commit bcb81ac6ae3c ("iommu: Get DT/ACPI parsing into the proper >>> probe path") broke virtio-iommu probing and no iommu group are >>> produced anymore. >>> >>> When probe_iommu_group() gets called viommu_probe_device() fails >>> because viommu_get_by_fwnode(fwspec->iommu_fwnode) returns NULL. >> >> ...which it's not supposed to. And *now* I remember, we never got this >> finished, did we? > Seems we did not ;-) >> >> https://lore.kernel.org/linux-iommu/9beaed48da83a0882dba153e65e6cfd0a8e21482.1742484773.git.robin.murphy@arm.com/ >> > > Unfortunately it does not fix my issue. Still no iommu group when > booting with ACPI. Indeed the evidence at the time suggested the patch isn't quite right as-is, but that is definitely the place which needs fixing. Since Jean-Philippe's occupied with more exciting things at the moment, do you happen to have an easy recipe for testing virtio-iommu so I can try debugging it myself? Cheers, Robin. > > Thanks > > Eric >> >> Thanks, >> Robin. >> >>> So it seems we need to restore the original iommu_probe_device >>> call site in acpi_iommu_configure_id() to get a chance to probe >>> the device again. >>> >>> Maybe this defeats the whole purpose of the original commit but >>> at least it fixes the virtio-iommu probing. >>> >>> Fixes: bcb81ac6ae3c ("iommu: Get DT/ACPI parsing into the proper >>> probe path") >>> Cc: stable@vger.kernel.org # v6.15+ >>> Signed-off-by: Eric Auger >>> >>> --- >>> >>> I also tested smmu probing and this seems to work fine. >>> --- >>>   drivers/acpi/scan.c | 7 +++++++ >>>   1 file changed, 7 insertions(+) >>> >>> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c >>> index fb1fe9f3b1a3..9f4efa8f75a6 100644 >>> --- a/drivers/acpi/scan.c >>> +++ b/drivers/acpi/scan.c >>> @@ -1632,6 +1632,13 @@ static int acpi_iommu_configure_id(struct >>> device *dev, const u32 *id_in) >>>           err = viot_iommu_configure(dev); >>>       mutex_unlock(&iommu_probe_device_lock); >>>   +    /* >>> +     * If we have reason to believe the IOMMU driver missed the initial >>> +     * iommu_probe_device() call for dev, replay it to get things in >>> order. >>> +     */ >>> +    if (!err && dev->bus) >>> +        err = iommu_probe_device(dev); >>> + >>>       return err; >>>   } >>> >> >