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Date: Tue, 15 Mar 2016 12:40:06 +0200
Message-ID: <CAJ3xEMhxUuQj+E00fa-tEKz+dVzDqFspC80Z=k7UPZpOP30H3g@mail.gmail.com>
Subject: Re: [RFC PATCH kernel] Revert "net/mlx4_core: Set UAR page size to
 4KB regardless of system page size"
From: Or Gerlitz <gerlitz.or@gmail.com>
To: Alexey Kardashevskiy <aik@ozlabs.ru>, Huy Nguyen <huyn@mellanox.com>
Cc: Doug Ledford <dledford@redhat.com>,
        Eugenia Emantayev <eugenia@mellanox.com>,
        Hal Rosenstock <hal.rosenstock@gmail.com>,
        Sean Hefty <sean.hefty@intel.com>, Yishai Hadas <yishaih@mellanox.com>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
        Linux Netdev List <netdev@vger.kernel.org>,
        Paul Mackerras <paulus@samba.org>, Carol L Soto <clsoto@us.ibm.com>,
        Yevgeny Petrilin <yevgenyp@mellanox.com>
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On Tue, Mar 15, 2016 at 12:19 PM, Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
> This reverts commit 85743f1eb34548ba4b056d2f184a3d107a3b8917.
>
> Without this revert, POWER "pseries" KVM guests with a VF passed to a guest
> using VFIO fail to bring the driver up:
>
> mlx4_core: Mellanox ConnectX core driver v2.2-1 (Feb, 2014)
> mlx4_core: Initializing 0000:00:00.0
> mlx4_core 0000:00:00.0: enabling device (0000 -> 0002)
> mlx4_core 0000:00:00.0: Detected virtual function - running in slave mode
> mlx4_core 0000:00:00.0: Sending reset
> mlx4_core 0000:00:00.0: Sending vhcr0
> mlx4_core 0000:00:00.0: HCA minimum page size:512
> mlx4_core 0000:00:00.0: UAR size:4096 != kernel PAGE_SIZE of 65536
> mlx4_core 0000:00:00.0: Failed to obtain slave caps

> Both host and guest use 64K system pages.
>
> How to fix this properly? Thanks.

The commit message says:

"[..] Regarding backward compatibility in SR-IOV, if hypervisor has
this new code, the virtual OS must be updated. [...]"


Or.