Re: [Xen-devel] [PATCH 4/4] x86/vmx: Drop vmx_msr_state infrastructure

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

> From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx]
> Sent: Monday, February 13, 2017 10:33 PM
> 
> To avoid leaking host MSR state into guests, guest LSTAR, STAR and
> SYSCALL_MASK state is unconditionally loaded when switching into guest
> context.
> 
> Attempting to dirty-track the state is pointless; host state is always
> restoring upon exit from guest context, meaning that guest state is always
> considered dirty.
> 
> Drop struct vmx_msr_state, enum VMX_INDEX_MSR_* and msr_index[].  The guests
> MSR values are stored plainly in arch_vmx_struct, in the same way as shadow_gs
> and cstar are.  vmx_restore_guest_msrs() and long_mode_do_msr_write() ensure
> that the hardware MSR values are always up-to-date.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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

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