Hi Catalin, On 10/08/17 17:57, James Morse wrote: > On 09/08/17 18:25, Catalin Marinas wrote: >> On Fri, Jul 28, 2017 at 03:10:09PM +0100, James Morse wrote: >>> @@ -520,9 +514,16 @@ el1_preempt: >>> el0_sync: >>> kernel_entry 0 >>> mrs x25, esr_el1 // read the syndrome register >>> + mrs x26, far_el1 >> >> Just checking, since we are going to access far_el1 even when we get a >> syscall, have you noticed any overhead? (I can get rid of the extra far_el1 reads by doing a better job of this patch.) > Good point, I haven't checked because I've been doing all this with the software > model. > > I will set this running on Seattle overnight, results in v3's cover letter. So the series does make microbenchmarks like calling getpid() in a loop slower, but its not the far_el1 read causing this, its the unconditional masking of exceptions in kernel_exit. This doesn't show up once I start doing real work (like fork or exec). I may be able to get rid of this but keep SError unmasked in the kernel and masked over eret by merging EL0-returns disable_daif with its existing irq-masked ret-to-user loop. Thanks, James _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
