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[34.127.79.33]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2eb392b15f0sm32087165ad.73.2026.11.02.10.59.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Nov 2026 10:59:58 -0800 (PST) Date: Mon, 2 Nov 2026 18:59:55 +0000 From: David Matlack To: Sean Christopherson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Alex Williamson , Paolo Bonzini , Shuah Khan Subject: Re: [PATCH 3/3] KVM: selftests: Use VFIO selftests library to pick IOMMU mode in IRQ test Message-ID: References: <20261029221710.1871112-1-dmatlack@google.com> <20261029221710.1871112-4-dmatlack@google.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On 2026-11-02 07:35 AM, Sean Christopherson wrote: > On Mon, Nov 02, 2026, Sean Christopherson wrote: > > On Thu, Oct 29, 2026, David Matlack wrote: > > > static void help(const char *name) > > > { > > > printf("Usage: %s [-a] [-d ] [-e] [-h] [-i nr_irqs] [-m] [-n] [-t iommu_type] [-v nr_vcpus] [-x]\n", name); > > > @@ -266,8 +250,7 @@ int main(int argc, char **argv) > > > } > > > > > > if (device_bdf) { > > > - if (!iommu_type) > > > - iommu_type = probe_iommu_type(); > > > + TEST_REQUIRE(iommu_mode_is_available(iommu_type)); > > > > This is very unhelpful when neither IOMMUFD nor VFIO is available, especially > > why the user doesn't explicitly provide the desired mode: > > > > # ./irq_test -d 0000:6f:01.0 -i 10000 > > Random seed: 0x79d386bd > > 1..0 # SKIP - Requirement not met: iommu_mode_is_available(iommu_type) Agreed, that is not very helpful. I've added a iommu_mode_unavailable_msg() helper to libvfio, which returns the reason a given mode (or any mode, if NULL) is not available. So irq_test would have: __TEST_REQUIRE(iommu_mode_is_available(iommu_type), "%s", iommu_mode_unavailable_msg(iommu_type)); which gives: # ./irq_test -d 0000:01:00.0 -t iommufd 1..0 # SKIP - IOMMU mode 'iommufd' is not available # ./irq_test -d 0000:01:00.0 1..0 # SKIP - No IOMMU mode is available. Is VFIO (or IOMMUFD) loaded and enabled? > Side topic, it would be nice if iommu_mode_lookup() printed out the known modes > when this is hit: > > VFIO_FAIL("Unrecognized IOMMU mode: %s\n", iommu_mode); Will do in v2. And I will also use the same helper to print out the list of known modes in irq_test -h.