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bh=rnDp5I6x3A3PSGWGNTcHDsvC0Hxz7VaObBC0sQPmk2o=; b=twU2fmUrnBpP6ZP4ZLcjRhEW4flqq+Xa+NF4TujYu+uonE9q0ekeBra2 dMqLNP5SUmgdXobnJMe+dWlM/HKZ3mGx+c/FNlAIT6kSXXC2tySxi9aez lzU8+To5xiCL7TxyR8yqyxAESiWDSFNbXQe+8ZsibjlBFfeUNyFRbtUUE o=; IronPort-SDR: MSGLE2U6Ywvdm0/7LZ2EFFZLSYATNkPwGtPzXiLLT7V5bdnlx5eTqZ85cjdTzmiDTvSDMabs5n CF2KXs+xJ+3A== X-IronPort-AV: E=Sophos;i="5.73,487,1583193600"; d="scan'208";a="50682291" Subject: Re: [PATCH 03/12] x86/xen: Introduce new function to map HYPERVISOR_shared_info on Resume Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-2a-22cc717f.us-west-2.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9102.sea19.amazon.com with ESMTP; 08 Jun 2020 16:53:01 +0000 Received: from EX13MTAUEB002.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2a-22cc717f.us-west-2.amazon.com (Postfix) with ESMTPS id B726EA221B; Mon, 8 Jun 2020 16:52:58 +0000 (UTC) Received: from EX13D08UEB003.ant.amazon.com (10.43.60.11) by EX13MTAUEB002.ant.amazon.com (10.43.60.12) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 8 Jun 2020 16:52:36 +0000 Received: from EX13MTAUEB002.ant.amazon.com (10.43.60.12) by EX13D08UEB003.ant.amazon.com (10.43.60.11) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 8 Jun 2020 16:52:36 +0000 Received: from dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com (172.22.96.68) by mail-relay.amazon.com (10.43.60.234) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Mon, 8 Jun 2020 16:52:36 +0000 Received: by dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com (Postfix, from userid 4335130) id C641640832; Mon, 8 Jun 2020 16:52:35 +0000 (UTC) Date: Mon, 8 Jun 2020 16:52:35 +0000 From: Anchal Agarwal To: Boris Ostrovsky Message-ID: <20200608165235.GA1330@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> References: <529f544a64bb93b920bf86b1d3f86d93b0a4219b.1589926004.git.anchalag@amazon.com> <72989b50-0c13-7a2b-19e2-de4a3646c83f@oracle.com> <20200604230307.GB25251@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> <9644a5f1-e1f8-5fe1-3135-cc6b4baf893b@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <9644a5f1-e1f8-5fe1-3135-cc6b4baf893b@oracle.com> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: Bulk X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: eduval@amazon.com, len.brown@intel.com, peterz@infradead.org, benh@kernel.crashing.org, x86@kernel.org, linux-mm@kvack.org, pavel@ucw.cz, hpa@zytor.com, sstabellini@kernel.org, kamatam@amazon.com, mingo@redhat.com, xen-devel@lists.xenproject.org, sblbir@amazon.com, axboe@kernel.dk, konrad.wilk@oracle.com, bp@alien8.de, tglx@linutronix.de, jgross@suse.com, netdev@vger.kernel.org, linux-pm@vger.kernel.org, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, vkuznets@redhat.com, davem@davemloft.net, dwmw@amazon.co.uk, roger.pau@citrix.com Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On Fri, Jun 05, 2020 at 05:39:54PM -0400, Boris Ostrovsky wrote: > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. > > > > On 6/4/20 7:03 PM, Anchal Agarwal wrote: > > On Sat, May 30, 2020 at 07:02:01PM -0400, Boris Ostrovsky wrote: > >> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. > >> > >> > >> > >> On 5/19/20 7:25 PM, Anchal Agarwal wrote: > >>> Introduce a small function which re-uses shared page's PA allocated > >>> during guest initialization time in reserve_shared_info() and not > >>> allocate new page during resume flow. > >>> It also does the mapping of shared_info_page by calling > >>> xen_hvm_init_shared_info() to use the function. > >>> > >>> Signed-off-by: Anchal Agarwal > >>> --- > >>> arch/x86/xen/enlighten_hvm.c | 7 +++++++ > >>> arch/x86/xen/xen-ops.h | 1 + > >>> 2 files changed, 8 insertions(+) > >>> > >>> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c > >>> index e138f7de52d2..75b1ec7a0fcd 100644 > >>> --- a/arch/x86/xen/enlighten_hvm.c > >>> +++ b/arch/x86/xen/enlighten_hvm.c > >>> @@ -27,6 +27,13 @@ > >>> > >>> static unsigned long shared_info_pfn; > >>> > >>> +void xen_hvm_map_shared_info(void) > >>> +{ > >>> + xen_hvm_init_shared_info(); > >>> + if (shared_info_pfn) > >>> + HYPERVISOR_shared_info = __va(PFN_PHYS(shared_info_pfn)); > >>> +} > >>> + > >> > >> AFAICT it is only called once so I don't see a need for new routine. > >> > >> > > HYPERVISOR_shared_info can only be mapped in this scope without refactoring > > much of the code. > > > Refactoring what? All am suggesting is > shared_info_pfn does not seem to be in scope here, it's scope is limited to enlighten_hvm.c. That's the reason I introduced a new function there. > --- a/arch/x86/xen/suspend.c > +++ b/arch/x86/xen/suspend.c > @@ -124,7 +124,9 @@ static void xen_syscore_resume(void) > return; > > /* No need to setup vcpu_info as it's already moved off */ > - xen_hvm_map_shared_info(); > + xen_hvm_init_shared_info(); > + if (shared_info_pfn) > + HYPERVISOR_shared_info = __va(PFN_PHYS(shared_info_pfn)); > > pvclock_resume(); > > >> And is it possible for shared_info_pfn to be NULL in resume path (which > >> is where this is called)? > >> > >> > > I don't think it should be, still a sanity check but I don't think its needed there > > because hibernation will fail in any case if thats the case. > > > If shared_info_pfn is NULL you'd have problems long before hibernation > started. We set it in xen_hvm_guest_init() and never touch again. > > > In fact, I'd argue that it should be __ro_after_init. > > I agree, and I should have mentioned that I will remove that check and its not necessary as this gets mapped way early in the boot process. > > However, HYPERVISOR_shared_info does needs to be re-mapped on resume as its been > > marked to dummy address on suspend. Its also safe in case va changes. > > Does the answer your question? > > > I wasn't arguing whether HYPERVISOR_shared_info needs to be set, I was > only saying that shared_info_pfn doesn't need to be tested. > Got it. :) > > -boris > Thanks, Anchal >