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Peter Anvin" , linux-kernel@vger.kernel.org, Tom Lendacky Subject: Re: [PATCH v3 1/3] KVM: SVM: use vmsave/vmload for saving/restoring additional host state Message-ID: References: <20210105143749.557054-1-michael.roth@amd.com> <20210105143749.557054-2-michael.roth@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210105143749.557054-2-michael.roth@amd.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Jan 05, 2021, Michael Roth wrote: > @@ -3703,16 +3688,9 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, > if (sev_es_guest(svm->vcpu.kvm)) { > __svm_sev_es_vcpu_run(svm->vmcb_pa); > } else { > - __svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&svm->vcpu.arch.regs); > - > -#ifdef CONFIG_X86_64 > - native_wrmsrl(MSR_GS_BASE, svm->host.gs_base); > -#else > - loadsegment(fs, svm->host.fs); > -#ifndef CONFIG_X86_32_LAZY_GS > - loadsegment(gs, svm->host.gs); > -#endif > -#endif > + __svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&svm->vcpu.arch.regs, > + page_to_phys(per_cpu(svm_data, > + vcpu->cpu)->save_area)); Does this need to use __sme_page_pa()? > } > > /* ... > diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S > index 6feb8c08f45a..89f4e8e7bf0e 100644 > --- a/arch/x86/kvm/svm/vmenter.S > +++ b/arch/x86/kvm/svm/vmenter.S > @@ -33,6 +33,7 @@ > * __svm_vcpu_run - Run a vCPU via a transition to SVM guest mode > * @vmcb_pa: unsigned long > * @regs: unsigned long * (to guest registers) > + * @hostsa_pa: unsigned long > */ > SYM_FUNC_START(__svm_vcpu_run) > push %_ASM_BP > @@ -47,6 +48,9 @@ SYM_FUNC_START(__svm_vcpu_run) > #endif > push %_ASM_BX > > + /* Save @hostsa_pa */ > + push %_ASM_ARG3 > + > /* Save @regs. */ > push %_ASM_ARG2 > > @@ -154,6 +158,12 @@ SYM_FUNC_START(__svm_vcpu_run) > xor %r15d, %r15d > #endif > > + /* "POP" @hostsa_pa to RAX. */ > + pop %_ASM_AX > + > + /* Restore host user state and FS/GS base */ > + vmload %_ASM_AX This VMLOAD needs the "handle fault on reboot" goo. Seeing the code, I think I'd prefer to handle this in C code, especially if Paolo takes the svm_ops.h patch[*]. Actually, I think with that patch it'd make sense to move the existing VMSAVE+VMLOAD for the guest into svm.c, too. And completely unrelated, the fault handling in svm/vmenter.S can be cleaned up a smidge to eliminate the JMPs. Paolo, what do you think about me folding these patches into my series to do the above cleanups? And maybe sending a pull request for the end result? (I'd also like to add on a patch to use the user return MSR mechanism for MSR_TSC_AUX). [*] https://lkml.kernel.org/r/20201231002702.2223707-8-seanjc@google.com > + > pop %_ASM_BX > > #ifdef CONFIG_X86_64 > -- > 2.25.1 >