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Re: [PATCH v3] xen: introduce XENFEAT_direct_mapped and XENFEAT_not_direct_mapped



Hi Stefano,

On 12/03/2021 23:16, Stefano Stabellini wrote:
Introduce two feature flags to tell the domain whether it is
direct-mapped or not. It allows the guest kernel to make informed
decisions on things such as swiotlb-xen enablement.

The introduction of both flags (XENFEAT_direct_mapped and
XENFEAT_not_direct_mapped) allows the guest kernel to avoid any
guesswork if one of the two is present, or fallback to the current
checks if neither of them is present.

XENFEAT_direct_mapped is always set for not auto-translated guests.

For auto-translated guests, only Dom0 on ARM is direct-mapped. Also,
see is_domain_direct_mapped() which refers to auto-translated guests:
xen/include/asm-arm/domain.h:is_domain_direct_mapped
xen/include/asm-x86/domain.h:is_domain_direct_mapped

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>

Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

--
Julien Grall



 


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