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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 816EDC433EF for ; Thu, 21 Oct 2021 23:15:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F4CB60F57 for ; Thu, 21 Oct 2021 23:15:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232054AbhJUXRv (ORCPT ); Thu, 21 Oct 2021 19:17:51 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:28040 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231379AbhJUXRt (ORCPT ); Thu, 21 Oct 2021 19:17:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634858133; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IOA+s/1Nf+8zWpX+cZKkzgCkT8RQvyoggZtI9lV9zOI=; b=RENcTzaGXcc1GIi58H/gADyFqQaRjuYX+L1VgMzYhWWMEP92qzgsraFxqos3eMq7gvsnDZ XYtoLWytZRtCpgdF0QqRnR8ymzqFjAcWDLB4bP7YfdKc6nid1LkZIQzNIrT1kTmFVgSqlf YdmRWQ8jipJFOlTv201h+EHKdVk8WAM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-194-98inMFoGNmi5J-u9SqC73A-1; Thu, 21 Oct 2021 19:15:31 -0400 X-MC-Unique: 98inMFoGNmi5J-u9SqC73A-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3CE5C10A8E02; Thu, 21 Oct 2021 23:15:30 +0000 (UTC) Received: from starship (unknown [10.40.192.246]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2442618428; Thu, 21 Oct 2021 23:15:27 +0000 (UTC) Message-ID: <1179443c92488afee6ee462f43a80ca959924a9a.camel@redhat.com> Subject: Re: [PATCH 8/8] KVM: SEV-ES: go over the sev_pio_data buffer in multiple passes if needed From: Maxim Levitsky To: Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: fwilhelm@google.com, seanjc@google.com, oupton@google.com, stable@vger.kernel.org Date: Fri, 22 Oct 2021 02:15:26 +0300 In-Reply-To: <20211013165616.19846-9-pbonzini@redhat.com> References: <20211013165616.19846-1-pbonzini@redhat.com> <20211013165616.19846-9-pbonzini@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2021-10-13 at 12:56 -0400, Paolo Bonzini wrote: > The PIO scratch buffer is larger than a single page, and therefore > it is not possible to copy it in a single step to vcpu->arch/pio_data. > Bound each call to emulator_pio_in/out to a single page; keep > track of how many I/O operations are left in vcpu->arch.sev_pio_count, > so that the operation can be restarted in the complete_userspace_io > callback. > > For OUT, this means that the previous kvm_sev_es_outs implementation > becomes an iterator of the loop, and we can consume the sev_pio_data > buffer before leaving to userspace. > > For IN, instead, consuming the buffer and decreasing sev_pio_count > is always done in the complete_userspace_io callback, because that > is when the memcpy is done into sev_pio_data. > > Cc: stable@vger.kernel.org > Fixes: 7ed9abfe8e9f ("KVM: SVM: Support string IO operations for an SEV-ES guest") > Reported-by: Felix Wilhelm > Signed-off-by: Paolo Bonzini > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/x86.c | 73 +++++++++++++++++++++++++-------- > 2 files changed, 57 insertions(+), 17 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 6bed6c416c6c..5a0298aa56ba 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -703,6 +703,7 @@ struct kvm_vcpu_arch { > struct kvm_pio_request pio; > void *pio_data; > void *sev_pio_data; > + unsigned sev_pio_count; > > u8 event_exit_inst_len; > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index a485e185ad00..09c1e64495d3 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -12378,38 +12378,76 @@ int kvm_sev_es_mmio_read(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned int bytes, > EXPORT_SYMBOL_GPL(kvm_sev_es_mmio_read); > > static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size, > - unsigned int port, unsigned int count) > + unsigned int port); > + > +static int complete_sev_es_emulated_outs(struct kvm_vcpu *vcpu) > { > - int ret = emulator_pio_out(vcpu, size, port, > - vcpu->arch.sev_pio_data, count); > + vcpu->arch.pio.count = 0; > + if (vcpu->arch.sev_pio_count) > + return kvm_sev_es_outs(vcpu, > + vcpu->arch.pio.size, > + vcpu->arch.pio.port); > + return 1; > +} > + > +static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size, > + unsigned int port) > +{ > + for (;;) { > + unsigned int count = > + min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count); > + int ret = emulator_pio_out(vcpu, size, port, vcpu->arch.sev_pio_data, count); > + > + /* memcpy done already by emulator_pio_out. */ > + vcpu->arch.sev_pio_count -= count; > + vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size; > + if (!ret) > + break; > > - if (ret) { > /* Emulation done by the kernel. */ > - return ret; > + vcpu->arch.pio.count = 0; > + if (!vcpu->arch.sev_pio_count) > + return 1; > } > > - vcpu->arch.pio.count = 0; > + vcpu->arch.complete_userspace_io = complete_sev_es_emulated_outs; > return 0; > } > > -static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu) > +static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size, > + unsigned int port); > + > +static void __complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu) > { > - memcpy(vcpu->arch.sev_pio_data, vcpu->arch.pio_data, > - vcpu->arch.pio.count * vcpu->arch.pio.size); > - vcpu->arch.pio.count = 0; > + unsigned count = vcpu->arch.pio.count; > + complete_emulator_pio_in(vcpu, vcpu->arch.sev_pio_data); > + vcpu->arch.sev_pio_count -= count; > + vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size; > +} > > +static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu) > +{ > + __complete_sev_es_emulated_ins(vcpu); > + if (vcpu->arch.sev_pio_count) > + return kvm_sev_es_ins(vcpu, > + vcpu->arch.pio.size, > + vcpu->arch.pio.port); > return 1; > } > > static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size, > - unsigned int port, unsigned int count) > + unsigned int port) > { > - int ret = emulator_pio_in(vcpu, size, port, > - vcpu->arch.sev_pio_data, count); > + for (;;) { > + unsigned int count = > + min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count); > + if (!__emulator_pio_in(vcpu, size, port, count)) > + break; > > - if (ret) { > /* Emulation done by the kernel. */ > - return ret; > + __complete_sev_es_emulated_ins(vcpu); > + if (!vcpu->arch.sev_pio_count) > + return 1; > } > > vcpu->arch.complete_userspace_io = complete_sev_es_emulated_ins; > @@ -12421,8 +12459,9 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size, > int in) > { > vcpu->arch.sev_pio_data = data; > - return in ? kvm_sev_es_ins(vcpu, size, port, count) > - : kvm_sev_es_outs(vcpu, size, port, count); > + vcpu->arch.sev_pio_count = count; > + return in ? kvm_sev_es_ins(vcpu, size, port) > + : kvm_sev_es_outs(vcpu, size, port); > } > EXPORT_SYMBOL_GPL(kvm_sev_es_string_io); > I might have missed something, but it looks OK to me. i mostly checked how the code looks after applying this patch. Reviewed-by: Maxim Levitsky Note that I haven't run tested the patches as I don't currently test SEV-ES. Best regards, Maxim Levitsky