Re: [Xen-devel] [PATCH for-4.12] x86/p2m: Drop erroneous #VE-enabled check in ept_set_entry()

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx]
> Sent: Friday, January 25, 2019 2:28 AM
> 
> Code clearing the "Suppress VE" bit in an EPT entry isn't nececsserily
> running
> in current context.  In ALTP2M_external mode, it definitely is not, and in PV
> context, vcpu_altp2m(current) acts upon the HVM union.
> 
> Even if we could sensibly resolve the target vCPU, it may legitimately not be
> fully set up at this point, so rejecting the EPT modification would be buggy.
> 
> There is a path in hvm_hap_nested_page_fault() which explicitly emulates
> #VE
> in the cpu_has_vmx_virt_exceptions case, so the -EOPNOTSUPP part of this
> condition is also wrong.
> 
> Drop the !sve check entirely.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
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