On 18/08/2021 12:30, Marek Marczykowski-Górecki wrote: > set_xcr0() and set_msr_xss() use cached value to avoid setting the > register to the same value over and over. But suspend/resume implicitly > reset the registers and since percpu areas are not deallocated on > suspend anymore, the cache gets stale. > Reset the cache on resume, to ensure the next write will really hit the > hardware. Choose value 0, as it will never be a legitimate write to > those registers - and so, will force write (and cache update). > > Note the cache is used io get_xcr0() and get_msr_xss() too, but: > - set_xcr0() is called few lines below in xstate_init(), so it will > update the cache with appropriate value > - get_msr_xss() is not used anywhere - and thus not before any > set_msr_xss() that will fill the cache > > Fixes: aca2a985a55a "xen: don't free percpu areas during suspend" > Signed-off-by: Marek Marczykowski-Górecki <[email protected]>
I'd prefer to do this differently. As I said in the thread, there are other registers such as MSR_TSC_AUX which fall into the same category, and I'd like to make something which works systematically. ~Andrew
