Re: [Xen-devel] [RFC PATCH 4/4] arm/mem_access: Add software guest-page-table walk

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 04/30/2017 10:48 PM, Sergej Proskurin wrote:
> The function p2m_mem_access_check_and_get_page in mem_access.c
> translates a gva to an ipa by means of the hardware functionality
> implemented in the function gva_to_ipa. If mem_access is active,
> hardware-based gva to ipa translation might fail, as gva_to_ipa uses the
> guest's translation tables, access to which might be restricted by the
> active VTTBR. To address this issue, we perform the gva to ipa
> translation in software.
> 
> Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
> ---
> Cc: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
> Cc: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> ---
>  xen/arch/arm/mem_access.c | 140 
> +++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 139 insertions(+), 1 deletion(-)

My ARM knowledge is scant to say the least, and I have no way to test
this code, so I'll leave it to Tamas who has done some ARM work in the
past. In any case - to state the obvious - the main acks here I believe
are Julien and Stefano.


Thanks,
Razvan

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