From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:34246 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727019AbgGJH5K (ORCPT ); Fri, 10 Jul 2020 03:57:10 -0400 Received: by mail-wm1-f72.google.com with SMTP id c124so5664242wme.0 for ; Fri, 10 Jul 2020 00:57:06 -0700 (PDT) Subject: Re: [PATCH v6 3/5] KVM: PPC: clean up redundant kvm_run parameters in assembly References: <20200623131418.31473-1-tianjia.zhang@linux.alibaba.com> <20200623131418.31473-4-tianjia.zhang@linux.alibaba.com> From: Paolo Bonzini Message-ID: <8947174f-ce16-c076-e208-55e743d9fdf0@redhat.com> Date: Fri, 10 Jul 2020 09:57:02 +0200 MIME-Version: 1.0 In-Reply-To: <20200623131418.31473-4-tianjia.zhang@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Tianjia Zhang , tsbogend@alpha.franken.de, paulus@ozlabs.org, mpe@ellerman.id.au, benh@kernel.crashing.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@redhat.com, cohuck@redhat.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com, sean.j.christopherson@intel.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, maz@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, christoffer.dall@arm.com, peterx@redhat.com, thuth@redhat.com, chenhuacai@gmail.com Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org On 23/06/20 15:14, Tianjia Zhang wrote: > > /* Load non-volatile guest state from the vcpu */ > - VCPU_LOAD_NVGPRS(r4) > + VCPU_LOAD_NVGPRS(r3) > > kvm_start_lightweight: > /* Copy registers into shadow vcpu so we can access them in real mode */ > - mr r3, r4 > bl FUNC(kvmppc_copy_to_svcpu) > nop > - REST_GPR(4, r1) > + REST_GPR(3, r1) > > #ifdef CONFIG_PPC_BOOK3S_64 > /* Get the dcbz32 flag */ > @@ -146,7 +144,7 @@ after_sprg3_load: Below, there are a bunch of references to r3 and r4 left rldicl r3, r3, 0, 63 /* r3 &= 1 */ stb r3, HSTATE_RESTORE_HID5(r13) /* Load up guest SPRG3 value, since it's user readable */ lwz r3, VCPU_SHAREDBE(r4) <<< cmpwi r3, 0 ld r5, VCPU_SHARED(r4) <<< where r3 is also destroyed. So I'd rather have three patches: - one that is as small as possible, changing the prototypes and adding mr r4, r3 - one that entirely swaps out r3 and r4. This would be the hard one to review! - one that cleans up the prologue and epilogue But overall I think it's simplest to just leave out this patch. Paolo