Re: [Xen-devel] [PATCH] x86/pv: Fix the handing of writes to %dr7

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.03.18 at 20:13, <andrew.cooper3@xxxxxxxxxx> wrote:
> c/s 65e35549 "x86/PV: support data breakpoint extension registers"
> accidentally broke the handing of writes.  The call to activate_debugregs()
> doesn't write %dr7 as v->arch.debugreg[7] hasn't been updated yet, and the
> break skips the intended write to %dr7.

That's really odd, especially with the comment in activate_debugregs()
specifically stating that fact.

> Remove the break, causing execution to hit the write_debugreg(7, value); in
> context at the bottom of the hunk, which in turn causes hardware to be updated
> appropriately.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>



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