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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86: store cr4 during suspend/resume
On 10.12.2019 10:59, Andrew Cooper wrote: > On 09/12/2019 18:06, Roger Pau Monne wrote: >> Currently cr4 is not cached before suspension, and mmu_cr4_features is >> used in order to restore the expected cr4 value. This is correct so >> far because the tasklet that executes the suspend/resume code is >> running in the idle vCPU context. >> >> In order to make the code less fragile, explicitly save the current >> cr4 value before suspension, so that it can be restored afterwards. >> This ensures that the cr4 value cached in the cpu_info doesn't get out >> of sync after resume from suspension. >> >> Suggested-by: Jan Beulich <jbeulich@xxxxxxxx> >> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> > > Why? There is nothing fragile here. Suspend/resume is always in idle > context and loads of other logic already depends on this. > > I've been slowly stripping out redundant saved state like this. Where it's clearly redundant, this is fine. But I don't think it's sufficiently clear here, and going back to what was there before is imo generally less error prone than going to some fixed state. Furthermore I was hoping we could eventually do away with mmu_cr4_features. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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