Re: [Xen-devel] [PATCH v2 for-4.7 5/5] x86/hvm: Fix invalidation for emulated invlpg instructions

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

> From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx]
> Sent: Tuesday, May 10, 2016 2:28 AM
> 
> hap_invlpg() is reachable from the instruction emulator, which means
> introspection and tests using hvm_fep can end up here.  As such, crashing the
> domain is not an appropriate action to take.
> 
> Fixing this involves rearranging the callgraph.
> 
> paging_invlpg() is now the central entry point.  It first checks for the
> non-canonical NOP case, and calls ino the paging subsystem.  If a real flush
> is needed, it will call the appropriate handler for the vcpu.  This allows the
> PV callsites of paging_invlpg() to be simplified.
> 
> The sole user of hvm_funcs.invlpg_intercept() is altered to use
> paging_invlpg() instead, allowing the .invlpg_intercept() hook to be removed.
> 
> For both VMX and SVM, the existing $VENDOR_invlpg_intercept() is split in
> half.  $VENDOR_invlpg_intercept() stays as the intercept handler only (which
> just calls paging_invlpg()), and new $VENDOR_invlpg() functions do the
> ASID/VPID management.  These later functions are made available in hvm_funcs
> for paging_invlpg() to use.
> 
> As a result, correct ASID/VPID management occurs for the hvmemul path, even if
> it did not originate from an real hardware intercept.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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

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