From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCC92C433FE for ; Fri, 26 Nov 2021 17:10:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236074AbhKZRNU (ORCPT ); Fri, 26 Nov 2021 12:13:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230473AbhKZRLQ (ORCPT ); Fri, 26 Nov 2021 12:11:16 -0500 X-Greylist: delayed 459 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Fri, 26 Nov 2021 08:41:30 PST Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09282C0613A5 for ; Fri, 26 Nov 2021 08:41:29 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 35135622BA for ; Fri, 26 Nov 2021 16:33:49 +0000 (UTC) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.kernel.org (Postfix) with ESMTPS id C4A4AC9305F; Fri, 26 Nov 2021 16:33:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 smtp.kernel.org C4A4AC9305F Authentication-Results: smtp.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: smtp.kernel.org; spf=fail smtp.mailfrom=kernel.org Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mqeAT-0084kh-TO; Fri, 26 Nov 2021 16:33:46 +0000 Date: Fri, 26 Nov 2021 16:33:45 +0000 Message-ID: <87y25ac1w6.wl-maz@kernel.org> From: Marc Zyngier To: Ganapatrao Kulkarni Cc: catalin.marinas@arm.com, will@kernel.org, andre.przywara@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, darren@os.amperecomputing.com, D Scott Phillips Subject: Re: [PATCH 2/2] KVM: arm64: nv: fixup! Support multiple nested Stage-2 mmu structures In-Reply-To: References: <20211122095803.28943-1-gankulkarni@os.amperecomputing.com> <20211122095803.28943-3-gankulkarni@os.amperecomputing.com> <877dcwco1m.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: gankulkarni@os.amperecomputing.com, catalin.marinas@arm.com, will@kernel.org, andre.przywara@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, darren@os.amperecomputing.com, scott@os.amperecomputing.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org [Resending, as kernel.org just had a hickup] On Fri, 26 Nov 2021 05:59:00 +0000, Ganapatrao Kulkarni wrote: > > Hi Marc, > > On 25-11-2021 07:53 pm, Marc Zyngier wrote: > > On Mon, 22 Nov 2021 09:58:03 +0000, > > Ganapatrao Kulkarni wrote: > >> > >> Commit 1776c91346b6 ("KVM: arm64: nv: Support multiple nested Stage-2 mmu > >> structures")[1] added a function kvm_vcpu_init_nested which expands the > >> stage-2 mmu structures array when ever a new vCPU is created. The array > >> is expanded using krealloc() and results in a stale mmu address pointer > >> in pgt->mmu. Adding a fix to update the pointer with the new address after > >> successful krealloc. > >> > >> [1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/ > >> branch kvm-arm64/nv-5.13 > >> > >> Signed-off-by: Ganapatrao Kulkarni > >> --- > >> arch/arm64/kvm/nested.c | 9 +++++++++ > >> 1 file changed, 9 insertions(+) > >> > >> diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c > >> index 4ffbc14d0245..57ad8d8f4ee5 100644 > >> --- a/arch/arm64/kvm/nested.c > >> +++ b/arch/arm64/kvm/nested.c > >> @@ -68,6 +68,8 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) > >> num_mmus * sizeof(*kvm->arch.nested_mmus), > >> GFP_KERNEL | __GFP_ZERO); > >> if (tmp) { > >> + int i; > >> + > >> if (kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 1]) || > >> kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 2])) { > >> kvm_free_stage2_pgd(&tmp[num_mmus - 1]); > >> @@ -80,6 +82,13 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) > >> } > >> kvm->arch.nested_mmus = tmp; > >> + > >> + /* Fixup pgt->mmu after krealloc */ > >> + for (i = 0; i < kvm->arch.nested_mmus_size; i++) { > >> + struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i]; > >> + > >> + mmu->pgt->mmu = mmu; > >> + } > >> } > >> mutex_unlock(&kvm->lock); > > > > Another good catch. I've tweaked a bit to avoid some unnecessary > > repainting, see below. > > > > Thanks again, > > > > M. > > > > diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c > > index a4dfffa1dae0..92b225db59ac 100644 > > --- a/arch/arm64/kvm/nested.c > > +++ b/arch/arm64/kvm/nested.c > > @@ -66,8 +66,19 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) > > num_mmus = atomic_read(&kvm->online_vcpus) * 2; > > tmp = krealloc(kvm->arch.nested_mmus, > > num_mmus * sizeof(*kvm->arch.nested_mmus), > > - GFP_KERNEL | __GFP_ZERO); > > + GFP_KERNEL_ACCOUNT | __GFP_ZERO); > > if (tmp) { > > + /* > > + * If we went through a realocation, adjust the MMU > > Is it more precise to say? > > + * back-pointers in the pg_table structures. > * back-pointers in the pg_table structures of previous inits. Yes. I have added something along those lines. > > + */ > > + if (kvm->arch.nested_mmus != tmp) { > > + int i; > > + > > + for (i = 0; i < num_mms - 2; i++) > > + tmp[i].pgt->mmu = &tmp[i]; > > + } > > Thanks for this optimization, it saves 2 redundant iterations. > > + > > if (kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 1]) || > > kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 2])) { > > kvm_free_stage2_pgd(&tmp[num_mmus - 1]); > > > > Feel free to add, > Reviewed-by: Ganapatrao Kulkarni Given that this was a fixup, I haven't taken this tag. I will Cc you on the whole series, and you can give you tag on the whole patch if you are happy with it. BTW, I have now fixed the bug that was preventing L2 userspace from running (bad interaction with the pgtable code which was unhappy about my use of the SW bits when relaxing the permissions). You should now be able to test the whole series. Thanks, M. -- Without deviation from the norm, progress is not possible. -- Without deviation from the norm, progress is not possible.