[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH 2/2] Do not access /dev/mem in MSI-X PCI passthrough on Xen
- To: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Tue, 15 Nov 2022 09:14:07 +0100
- Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none
- Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=9HBNiTXovtNWiPwUqgQjYj2iqh2e87mFpE3f4n77bZ0=; b=OBjkt/3ylOpKPe2/OTSW2VOI8aPVbYvttA5DShNUym7eNdWAjZTnUg0KT8u82XIoucs45SJwM1Z6OToOXMbck832SRJDivVga0S4352XsdBPpPQDSULnnlrfLoyfBdR9ZGIScOJvyGxnL+Db/MDFiJTiZ2CgcQr2DbsESj+7bp43Fyjl9yINPNXefTT0r0wTh3pYqP6HMyDbeVlCkPr5ze/9PsFB5V10dYr3gXZ4WtOqIXSdtGgCxItsw1E63T1i9yNyERo9jil2U8BmC7i8Ecctwk/dShGgWKoDJCc9dBAlBzWQ5N9np9PhOTRNAtlnMVHhqN2CsOcuLf4aEqrnHg==
- Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=T/jzgcsWRS1HAo8MtPx+A2fqU6DvjAtEa2LHJD4Wl0oLcaJKAbK5N0rCNN8w18O9K7hcATZmf/nyHOS+VFyn1koIr7IrbTK5cZStpm6E6lb7eEQmxHScXDM8O+/INYPXGPkV14ATkHeTOJ5wBEkJrzBt3V2IEwMMky0Hq/2it7PtComRk3kXcCBj5lZAeUtk+fWAhK8wbIJPIgL9PI+O0N+HTVsii1szrRDc24UPdiYkJ5OTqNQECvN+K57QdKUhTCVY43pHRwvT9F1QDoGgEd5M9HfhjknZisKYtipyqDxUL0cY8y0hL5/iAggBq4hWhaytfydUkrULkuAF1Ewyhg==
- Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=suse.com;
- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Anthony Perard <anthony.perard@xxxxxxxxxx>, Paul Durrant <paul@xxxxxxx>, "open list:X86 Xen CPUs" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, qemu-devel@xxxxxxxxxx
- Delivery-date: Tue, 15 Nov 2022 08:14:23 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 14.11.2022 20:20, Marek Marczykowski-Górecki wrote:
> The /dev/mem is used for two purposes:
> - reading PCI_MSIX_ENTRY_CTRL_MASKBIT
> - reading Pending Bit Array (PBA)
>
> The first one was originally done because when Xen did not send all
> vector ctrl writes to the device model, so QEMU might have outdated old
> register value. This has been changed in Xen, so QEMU can now use its
> cached value of the register instead.
>
> The Pending Bit Array (PBA) handling is for the case where it lives on
> the same page as the MSI-X table itself. Xen has been extended to handle
> this case too (as well as other registers that may live on those pages),
> so QEMU handling is not necessary anymore.
Don't you need to check for new enough Xen for both aspects?
Jan
|
