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 1542BC433EF for ; Tue, 22 Feb 2022 14:35:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232847AbiBVOfy (ORCPT ); Tue, 22 Feb 2022 09:35:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231429AbiBVOfw (ORCPT ); Tue, 22 Feb 2022 09:35:52 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B86015D3B0 for ; Tue, 22 Feb 2022 06:35:27 -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 D8FB861490 for ; Tue, 22 Feb 2022 14:35:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C197C340F0; Tue, 22 Feb 2022 14:35:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1645540526; bh=B8WPOv6gSd5v+BIfW9xCsGRHlve1K9J3Jg3fIJWk9Ro=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=dqeDcMsttdAFUPRkpjgynHT5BdH+in3TaGa6UVWy/K58D9DtDSGG0ZmV+/JlSdq5v 0kKPRt+DjkwuUSbctgK/zR/yqiAqFJpKtFrXXtjYN+x4rKwOa8lDP2tAluSQ9qhu0q S3BPl/zeA9N5H+tvaT0qiPawwm2r+2KAIVVe4Iz6EVnTjLRC7whvSQqznxFtZx2hHs 0qCMEvRjQJQA4n4/bUk0xYAe/SZn7T1nNVdaN/uLLg513n8vmo5w0ROYqsrhbdWo5n pQZZwU5TJdpZhBCbgTI03YsiCvmDB4noeBpmp8tlHwMn3mk5+49y4+nT2qPYMklMF9 hxpgWnvP8FCHQ== Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) 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 1nMWGC-009Yvi-5h; Tue, 22 Feb 2022 14:35:24 +0000 MIME-Version: 1.0 Date: Tue, 22 Feb 2022 14:35:24 +0000 From: Marc Zyngier To: Alexandru Elisei Cc: Sebastian Ene , kvm@vger.kernel.org, will@kernel.org, kvmarm@lists.cs.columbia.edu Subject: Re: [PATCH kvmtool v3] aarch64: Add stolen time support In-Reply-To: References: User-Agent: Roundcube Webmail/1.4.13 Message-ID: <2772b40f99a30ecd475fa83641d40994@kernel.org> X-Sender: maz@kernel.org Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: alexandru.elisei@arm.com, sebastianene@google.com, kvm@vger.kernel.org, will@kernel.org, kvmarm@lists.cs.columbia.edu 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 On 2022-02-22 14:28, Alexandru Elisei wrote: > Hi, > > On Tue, Feb 22, 2022 at 02:18:40PM +0000, Marc Zyngier wrote: >> On 2022-02-22 13:58, Alexandru Elisei wrote: >> > Hi, >> > >> > On Tue, Feb 22, 2022 at 10:08:30AM +0000, Sebastian Ene wrote: >> > > This patch adds support for stolen time by sharing a memory region >> > > with the guest which will be used by the hypervisor to store the >> > > stolen >> > > time information. The exact format of the structure stored by the >> > > hypervisor is described in the ARM DEN0057A document. >> > > >> > > Signed-off-by: Sebastian Ene >> > > --- >> > > Changelog since v2: >> > > - Moved the AARCH64_PVTIME_* definitions from arm-common/kvm-arch.h >> > > to >> > > arm64/pvtime.c as pvtime is only available for arm64. >> > > >> > > Changelog since v1: >> > > - Removed the pvtime.h header file and moved the definitions to >> > > kvm-cpu-arch.h >> > > Verified if the stolen time capability is supported before >> > > allocating >> > > and mapping the memory. >> > > >> > > Makefile | 1 + >> > > arm/aarch64/arm-cpu.c | 1 + >> > > arm/aarch64/include/kvm/kvm-cpu-arch.h | 1 + >> > > arm/aarch64/pvtime.c | 89 >> > > ++++++++++++++++++++++++++ >> > > arm/kvm-cpu.c | 14 ++-- >> > > 5 files changed, 99 insertions(+), 7 deletions(-) >> > > create mode 100644 arm/aarch64/pvtime.c >> > > >> > > diff --git a/Makefile b/Makefile >> > > index f251147..e9121dc 100644 >> > > --- a/Makefile >> > > +++ b/Makefile >> > > @@ -182,6 +182,7 @@ ifeq ($(ARCH), arm64) >> > > OBJS += arm/aarch64/arm-cpu.o >> > > OBJS += arm/aarch64/kvm-cpu.o >> > > OBJS += arm/aarch64/kvm.o >> > > + OBJS += arm/aarch64/pvtime.o >> > > ARCH_INCLUDE := $(HDRS_ARM_COMMON) >> > > ARCH_INCLUDE += -Iarm/aarch64/include >> > > >> > > diff --git a/arm/aarch64/arm-cpu.c b/arm/aarch64/arm-cpu.c >> > > index d7572b7..326fb20 100644 >> > > --- a/arm/aarch64/arm-cpu.c >> > > +++ b/arm/aarch64/arm-cpu.c >> > > @@ -22,6 +22,7 @@ static void generate_fdt_nodes(void *fdt, struct >> > > kvm *kvm) >> > > static int arm_cpu__vcpu_init(struct kvm_cpu *vcpu) >> > > { >> > > vcpu->generate_fdt_nodes = generate_fdt_nodes; >> > > + kvm_cpu__setup_pvtime(vcpu); >> > > return 0; >> > > } >> > > >> > > diff --git a/arm/aarch64/include/kvm/kvm-cpu-arch.h >> > > b/arm/aarch64/include/kvm/kvm-cpu-arch.h >> > > index 8dfb82e..b57d6e6 100644 >> > > --- a/arm/aarch64/include/kvm/kvm-cpu-arch.h >> > > +++ b/arm/aarch64/include/kvm/kvm-cpu-arch.h >> > > @@ -19,5 +19,6 @@ >> > > >> > > void kvm_cpu__select_features(struct kvm *kvm, struct kvm_vcpu_init >> > > *init); >> > > int kvm_cpu__configure_features(struct kvm_cpu *vcpu); >> > > +void kvm_cpu__setup_pvtime(struct kvm_cpu *vcpu); >> > > >> > > #endif /* KVM__KVM_CPU_ARCH_H */ >> > > diff --git a/arm/aarch64/pvtime.c b/arm/aarch64/pvtime.c >> > > new file mode 100644 >> > > index 0000000..247e4f3 >> > > --- /dev/null >> > > +++ b/arm/aarch64/pvtime.c >> > > @@ -0,0 +1,89 @@ >> > > +#include "kvm/kvm.h" >> > > +#include "kvm/kvm-cpu.h" >> > > +#include "kvm/util.h" >> > > + >> > > +#include >> > > +#include >> > > + >> > > +#define AARCH64_PVTIME_IPA_MAX_SIZE SZ_64K >> > > +#define AARCH64_PVTIME_IPA_START (ARM_MEMORY_AREA - \ >> > > + AARCH64_PVTIME_IPA_MAX_SIZE) >> > >> > This doesn't change the fact that it overlaps with KVM_PCI_MMIO_AREA, >> > which is >> > exposed to the guest in the DTB (see my reply to v2). >> >> Yup, this is a bit of a problem, and overlapping regions are >> a big no-no. Why can't the pvtime region be dynamically placed >> after the RAM (after checking that there is enough space to >> register it in the IPA space)? > > In theory, is there something to stop someone from creating a VM with > enough > memory to reach the end of the IPA space? No, but we can either steal 64kB from that upper limit if that's the case, or let the user know that stolen time is disabled because they have been greedy... M. -- Jazz is not dead. It just smells funny...