From: Paul Mackerras Date: Thu, 11 Feb 2021 06:09:45 +0000 (+1100) Subject: KVM: PPC: Book3S HV: Ensure radix guest has no SLB entries X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ab950e1acd2175eae825cfcbac621c0625ad2a86;p=linux.git KVM: PPC: Book3S HV: Ensure radix guest has no SLB entries Commit 68ad28a4cdd4 ("KVM: PPC: Book3S HV: Fix radix guest SLB side channel") changed the older guest entry path, with the side effect that vcpu->arch.slb_max no longer gets cleared for a radix guest. This means that a HPT guest which loads some SLB entries, switches to radix mode, runs the guest using the old guest entry path (e.g., because the indep_threads_mode module parameter has been set to false), and then switches back to HPT mode would now see the old SLB entries being present, whereas previously it would have seen no SLB entries. To avoid changing guest-visible behaviour, this adds a store instruction to clear vcpu->arch.slb_max for a radix guest using the old guest entry path. Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 426bdc59fde24..0bc1c8248050b 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -1539,8 +1539,12 @@ guest_exit_cont: /* r9 = vcpu, r12 = trap, r13 = paca */ .endr b guest_bypass -0: /* Sanitise radix guest SLB, see guest_exit_short_path comment. */ +0: /* + * Sanitise radix guest SLB, see guest_exit_short_path comment. + * We clear vcpu->arch.slb_max to match earlier behaviour. + */ li r0,0 + stw r0,VCPU_SLB_MAX(r9) slbmte r0,r0 li r4,1 slbmte r0,r4