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[2003:ea:8f06:5500:20b9:2450:6471:c6e0]) by smtp.googlemail.com with ESMTPSA id v126sm396523wma.22.2021.01.25.12.06.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 Jan 2021 12:06:06 -0800 (PST) To: Cornelia Huck Cc: Alex Williamson , kvm@vger.kernel.org References: <3d14987b-278c-be28-be7b-8f3c733fc4e9@gmail.com> <20210125191147.5f876923.cohuck@redhat.com> From: Heiner Kallweit Subject: Re: [PATCH] vfio/pci: Fix handling of pci use accessor return codes Message-ID: <1b4b36a2-edfd-bde1-a265-cb9b0272bd55@gmail.com> Date: Mon, 25 Jan 2021 21:06:03 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210125191147.5f876923.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 25.01.2021 19:11, Cornelia Huck wrote: > On Sun, 24 Jan 2021 16:35:41 +0100 > Heiner Kallweit wrote: > >> The pci user accessors return negative errno's on error. >> >> Fixes: f572a960a15e ("vfio/pci: Intel IGD host and LCP bridge config space access") >> Signed-off-by: Heiner Kallweit >> --- >> drivers/vfio/pci/vfio_pci_igd.c | 10 +++++----- >> 1 file changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/vfio/pci/vfio_pci_igd.c b/drivers/vfio/pci/vfio_pci_igd.c >> index 53d97f459..e66dfb017 100644 >> --- a/drivers/vfio/pci/vfio_pci_igd.c >> +++ b/drivers/vfio/pci/vfio_pci_igd.c >> @@ -127,7 +127,7 @@ static size_t vfio_pci_igd_cfg_rw(struct vfio_pci_device *vdev, >> >> ret = pci_user_read_config_byte(pdev, pos, &val); >> if (ret) >> - return pcibios_err_to_errno(ret); >> + return ret; > > This is actually not strictly needed, as pcibios_err_to_errno() already > keeps errors <= 0 unchanged, so more a cleanup than a fix? > I agree. Although I'd argue that the author of the original commit missed the fact the the user accessors return errno's, and the code just works by chance, because of the "good will" of pcibios_err_to_errno(). So up to you whether it's worth it to apply this change also to stable. > Anyway, > > Reviewed-by: Cornelia Huck > >> >> if (copy_to_user(buf + count - size, &val, 1)) >> return -EFAULT; >