On 04/06/18 14:59, Andrew Cooper wrote:
> c/s 4f36452b63 introduced a write to %dr6 in the #DB intercept case, but the
> guests debug registers may be lazy at this point, at which point the guests
> later attempt to read %dr6 will discard this value and use the older stale
> value.
>
> Signed-off-by: Andrew Cooper <[email protected]>
> ---
> CC: Jan Beulich <[email protected]>
> CC: Wei Liu <[email protected]>
> CC: Roger Pau Monné <[email protected]>
> CC: Jun Nakajima <[email protected]>
> CC: Kevin Tian <[email protected]>
Ping
> ---
> xen/arch/x86/hvm/vmx/vmx.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> index 33d39f6..8dbe838 100644
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -3696,6 +3696,7 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
> */
> __vmread(EXIT_QUALIFICATION, &exit_qualification);
> HVMTRACE_1D(TRAP_DEBUG, exit_qualification);
> + __restore_debug_registers(v);
> write_debugreg(6, exit_qualification | DR_STATUS_RESERVED_ONE);
> if ( !v->domain->debugger_attached )
> {
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