Re: [PATCH v5 0/2] KVM: MMU: fix kvm_is_mmio_pfn()

From: Xiao Guangrong
Date: Wed Nov 08 2017 - 04:19:21 EST




On 11/08/2017 03:56 PM, Haozhong Zhang wrote:
Some reserved pages, such as those from NVDIMM DAX devices, are not
for MMIO, and can be mapped with cached memory type for better
performance. However, the above check misconceives those pages as
MMIO. Because KVM maps MMIO pages with UC memory type, the
performance of guest accesses to those pages would be harmed.
Therefore, we check the host memory type in addition and only treat
UC/UC- pages as MMIO.


Reviewed-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxx>