Re: [PATCH v5 11/14] nEPT: MMU context for nested EPT

Xiao Guangrong
2013-08-01T09:16:17Z

On 07/31/2013 10:48 PM, Gleb Natapov wrote:
> From: Nadav Har'El <nyh@il.ibm.com>
>
> KVM's existing shadow MMU code already supports nested TDP. To use it, we
> need to set up a new "MMU context" for nested EPT, and create a few callbacks
> for it (nested_ept_*()). This context should also use the EPT versions of
> the page table access functions (defined in the previous patch).
> Then, we need to switch back and forth between this nested context and the
> regular MMU context when switching between L1 and L2 (when L1 runs this L2
> with EPT).

This patch looks good to me.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>

But i am confused that update_permission_bitmask() is not adjusted in this
series. That function depends on kvm_read_cr4_bits(X86_CR4_SMEP) and
is_write_protection(), these two functions should read the registers from
L2 guest, using the L2 status to check L1's page table seems strange.
The same issue is in nested npt. Anything i missed?