Hey Marc, On Monday 22 Mar 2021 at 16:48:27 (+0000), Marc Zyngier wrote: > In protected mode, late CPUs are not allowed to boot (enforced by > the PSCI relay). We can thus specialise the read_ctr macro to > always return a pre-computed, sanitised value. > > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > --- > arch/arm64/include/asm/assembler.h | 9 +++++++++ > arch/arm64/kernel/image-vars.h | 1 + > arch/arm64/kvm/va_layout.c | 7 +++++++ > 3 files changed, 17 insertions(+) > > diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h > index fb651c1f26e9..1a4cee7eb3c9 100644 > --- a/arch/arm64/include/asm/assembler.h > +++ b/arch/arm64/include/asm/assembler.h > @@ -270,12 +270,21 @@ alternative_endif > * provide the system wide safe value from arm64_ftr_reg_ctrel0.sys_val > */ > .macro read_ctr, reg > +#ifndef __KVM_NVHE_HYPERVISOR__ > alternative_if_not ARM64_MISMATCHED_CACHE_TYPE > mrs \reg, ctr_el0 // read CTR > nop > alternative_else > ldr_l \reg, arm64_ftr_reg_ctrel0 + ARM64_FTR_SYSVAL > alternative_endif > +#else > +alternative_cb kvm_compute_final_ctr_el0 > + movz \reg, #0 > + movk \reg, #0, lsl #16 > + movk \reg, #0, lsl #32 > + movk \reg, #0, lsl #48 > +alternative_cb_end > +#endif > .endm So, FWIW, if we wanted to make _this_ macro BUG in non-protected mode (and drop patch 01), I think we could do something like: alternative_cb kvm_compute_final_ctr_el0 movz \reg, #0 ASM_BUG() nop nop alternative_cb_end and then make kvm_compute_final_ctr_el0() check that we're in protected mode before patching. That would be marginally better as that would cover _all_ users of read_ctr and not just __flush_dcache_area, but that first movz is a bit yuck (but necessary to keep generate_mov_q() happy I think?), so I'll leave the decision to you. No objection from me for the current implementation, and if you decide to go with it: Reviewed-by: Quentin Perret <qperret@xxxxxxxxxx> Thanks, Quentin _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
