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 395416110; Tue, 5 Dec 2023 03:25:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="D6rz2l27" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 709AFC433C7; Tue, 5 Dec 2023 03:25:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1701746751; bh=YfhqTc/8qe+XBrebp05O5/yFvqA+1pU8BQu5NUL6Pj0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D6rz2l273EfT9aDEp5JtxDSZIZa2itKsqYH1lscv3JMu5+UR/ALUWaisH6K3pKGk7 iPY4+Nm410EJlR9tyRJ5SyDfLIDuxERYxbrJ5rBBv3+GNFCDsXYR0Jou1uhISz2Qzn s1X1Mn+L05PDjj5rUADhp22OxpM7LUfNTS/aVZH4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, kernel test robot , Nick Desaulniers , Jason Gunthorpe , Michael Ellerman , Sean Christopherson , Alex Williamson , Sasha Levin Subject: [PATCH 6.6 134/134] vfio: Drop vfio_file_iommu_group() stub to fudge around a KVM wart Date: Tue, 5 Dec 2023 12:16:46 +0900 Message-ID: <20231205031543.944552356@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231205031535.163661217@linuxfoundation.org> References: <20231205031535.163661217@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sean Christopherson [ Upstream commit 4ea95c04fa6b9043a1a301240996aeebe3cb28ec ] Drop the vfio_file_iommu_group() stub and instead unconditionally declare the function to fudge around a KVM wart where KVM tries to do symbol_get() on vfio_file_iommu_group() (and other VFIO symbols) even if CONFIG_VFIO=n. Ensuring the symbol is always declared fixes a PPC build error when modules are also disabled, in which case symbol_get() simply points at the address of the symbol (with some attributes shenanigans). Because KVM does symbol_get() instead of directly depending on VFIO, the lack of a fully defined symbol is not problematic (ugly, but "fine"). arch/powerpc/kvm/../../../virt/kvm/vfio.c:89:7: error: attribute declaration must precede definition [-Werror,-Wignored-attributes] fn = symbol_get(vfio_file_iommu_group); ^ include/linux/module.h:805:60: note: expanded from macro 'symbol_get' #define symbol_get(x) ({ extern typeof(x) x __attribute__((weak,visibility("hidden"))); &(x); }) ^ include/linux/vfio.h:294:35: note: previous definition is here static inline struct iommu_group *vfio_file_iommu_group(struct file *file) ^ arch/powerpc/kvm/../../../virt/kvm/vfio.c:89:7: error: attribute declaration must precede definition [-Werror,-Wignored-attributes] fn = symbol_get(vfio_file_iommu_group); ^ include/linux/module.h:805:65: note: expanded from macro 'symbol_get' #define symbol_get(x) ({ extern typeof(x) x __attribute__((weak,visibility("hidden"))); &(x); }) ^ include/linux/vfio.h:294:35: note: previous definition is here static inline struct iommu_group *vfio_file_iommu_group(struct file *file) ^ 2 errors generated. Although KVM is firmly in the wrong (there is zero reason for KVM to build virt/kvm/vfio.c when VFIO is disabled), fudge around the error in VFIO as the stub is unnecessary and doesn't serve its intended purpose (KVM is the only external user of vfio_file_iommu_group()), and there is an in-flight series to clean up the entire KVM<->VFIO interaction, i.e. fixing this in KVM would result in more churn in the long run, and the stub needs to go away regardless. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202308251949.5IiaV0sz-lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202309030741.82aLACDG-lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202309110914.QLH0LU6L-lkp@intel.com Link: https://lore.kernel.org/all/0-v1-08396538817d+13c5-vfio_kvm_kconfig_jgg@nvidia.com Link: https://lore.kernel.org/all/20230916003118.2540661-1-seanjc@google.com Cc: Nick Desaulniers Cc: Jason Gunthorpe Tested-by: Michael Ellerman Fixes: c1cce6d079b8 ("vfio: Compile vfio_group infrastructure optionally") Signed-off-by: Sean Christopherson Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/20231130001000.543240-1-seanjc@google.com Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin --- include/linux/vfio.h | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/include/linux/vfio.h b/include/linux/vfio.h index 454e9295970c4..a65b2513f8cdc 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -289,16 +289,12 @@ void vfio_combine_iova_ranges(struct rb_root_cached *root, u32 cur_nodes, /* * External user API */ -#if IS_ENABLED(CONFIG_VFIO_GROUP) struct iommu_group *vfio_file_iommu_group(struct file *file); + +#if IS_ENABLED(CONFIG_VFIO_GROUP) bool vfio_file_is_group(struct file *file); bool vfio_file_has_dev(struct file *file, struct vfio_device *device); #else -static inline struct iommu_group *vfio_file_iommu_group(struct file *file) -{ - return NULL; -} - static inline bool vfio_file_is_group(struct file *file) { return false; -- 2.42.0