From patchwork Mon Mar 9 09:35:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 11426505 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E8D5A92A for ; Mon, 9 Mar 2020 09:37:05 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CF5BD20727 for ; Mon, 9 Mar 2020 09:37:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF5BD20727 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jBEpP-0003H3-NM; Mon, 09 Mar 2020 09:36:03 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jBEpO-0003GR-7X for xen-devel@lists.xenproject.org; Mon, 09 Mar 2020 09:36:02 +0000 X-Inumbo-ID: 61d0661c-61e9-11ea-90c4-bc764e2007e4 Received: from smtp-fw-6001.amazon.com (unknown [52.95.48.154]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 61d0661c-61e9-11ea-90c4-bc764e2007e4; Mon, 09 Mar 2020 09:35:58 +0000 (UTC) IronPort-SDR: x1uLXetG4eBM3i1YZmv0wt3HEaL0Pzluo44ajVqbR5+iK7TLHmcEb6jHeQnE2iSq4SdBSUvcCZ Y8kGYz3m9Nhg== X-IronPort-AV: E=Sophos;i="5.70,532,1574121600"; d="scan'208";a="21620247" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-2b-c7131dcf.us-west-2.amazon.com) ([10.43.8.6]) by smtp-border-fw-out-6001.iad6.amazon.com with ESMTP; 09 Mar 2020 09:35:56 +0000 Received: from EX13MTAUEA002.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan2.pdx.amazon.com [10.170.41.162]) by email-inbound-relay-2b-c7131dcf.us-west-2.amazon.com (Postfix) with ESMTPS id B83E5A28ED; Mon, 9 Mar 2020 09:35:55 +0000 (UTC) Received: from EX13D32EUB003.ant.amazon.com (10.43.166.165) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1236.3; Mon, 9 Mar 2020 09:35:27 +0000 Received: from EX13MTAUEA001.ant.amazon.com (10.43.61.82) by EX13D32EUB003.ant.amazon.com (10.43.166.165) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 9 Mar 2020 09:35:26 +0000 Received: from u2f063a87eabd5f.cbg10.amazon.com (10.125.106.135) by mail-relay.amazon.com (10.43.61.243) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Mon, 9 Mar 2020 09:35:24 +0000 From: To: Date: Mon, 9 Mar 2020 09:35:11 +0000 Message-ID: <20200309093511.1727-7-paul@xen.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200309093511.1727-1-paul@xen.org> References: <20200309093511.1727-1-paul@xen.org> MIME-Version: 1.0 Precedence: Bulk Subject: [Xen-devel] [PATCH v4 6/6] domain: use PGC_extra domheap page for shared_info X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Stefano Stabellini , Julien Grall , Wei Liu , Paul Durrant , Andrew Cooper , Paul Durrant , Konrad Rzeszutek Wilk , Ian Jackson , George Dunlap , Jan Beulich , Volodymyr Babchuk Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" From: Paul Durrant Currently shared_info is a shared xenheap page but shared xenheap pages complicate future plans for live-update of Xen so it is desirable to, where possible, not use them [1]. This patch therefore converts shared_info into a PGC_extra domheap page. This does entail freeing shared_info during domain_relinquish_resources() rather than domain_destroy() so care is needed to avoid de-referencing a NULL shared_info pointer hence some extra checks of 'is_dying' are needed. NOTE: For Arm, the call to free_shared_info() in arch_domain_destroy() is left in place since it is idempotent and called in the error path for arch_domain_create(). [1] See https://lists.xenproject.org/archives/html/xen-devel/2020-02/msg02018.html Signed-off-by: Paul Durrant --- Cc: Stefano Stabellini Cc: Julien Grall Cc: Volodymyr Babchuk Cc: Andrew Cooper Cc: George Dunlap Cc: Ian Jackson Cc: Jan Beulich Cc: Konrad Rzeszutek Wilk Cc: Wei Liu v2: - Addressed comments from Julien - Expanded the commit comment to explain why this patch is wanted --- xen/arch/arm/domain.c | 2 ++ xen/arch/x86/domain.c | 3 ++- xen/common/domain.c | 28 ++++++++++++++++++++++++---- xen/common/event_channel.c | 3 +++ xen/common/time.c | 15 +++++++++++++++ 5 files changed, 46 insertions(+), 5 deletions(-) diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c index 5298d80bd2..741f6dd444 100644 --- a/xen/arch/arm/domain.c +++ b/xen/arch/arm/domain.c @@ -1005,6 +1005,8 @@ int domain_relinquish_resources(struct domain *d) BUG(); } + free_shared_info(d); + return 0; } diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c index f6ed25e8ee..d962835f33 100644 --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -693,7 +693,6 @@ void arch_domain_destroy(struct domain *d) pv_domain_destroy(d); free_perdomain_mappings(d); - free_shared_info(d); cleanup_domain_irq_mapping(d); psr_domain_free(d); @@ -2249,6 +2248,8 @@ int domain_relinquish_resources(struct domain *d) if ( is_hvm_domain(d) ) hvm_domain_relinquish_resources(d); + free_shared_info(d); + return 0; } diff --git a/xen/common/domain.c b/xen/common/domain.c index ba7a905258..886206f648 100644 --- a/xen/common/domain.c +++ b/xen/common/domain.c @@ -1650,24 +1650,44 @@ int continue_hypercall_on_cpu( int alloc_shared_info(struct domain *d, unsigned int memflags) { - if ( (d->shared_info.virt = alloc_xenheap_pages(0, memflags)) == NULL ) + struct page_info *pg; + + pg = alloc_domheap_page(d, MEMF_no_refcount | memflags); + if ( !pg ) return -ENOMEM; - d->shared_info.mfn = virt_to_mfn(d->shared_info.virt); + if ( !get_page_and_type(pg, d, PGT_writable_page) ) + { + /* + * The domain should not be running at this point so there is + * no way we should reach this error path. + */ + ASSERT_UNREACHABLE(); + return -ENODATA; + } + + d->shared_info.mfn = page_to_mfn(pg); + d->shared_info.virt = __map_domain_page_global(pg); clear_page(d->shared_info.virt); - share_xen_page_with_guest(mfn_to_page(d->shared_info.mfn), d, SHARE_rw); return 0; } void free_shared_info(struct domain *d) { + struct page_info *pg; + if ( !d->shared_info.virt ) return; - free_xenheap_page(d->shared_info.virt); + unmap_domain_page_global(d->shared_info.virt); d->shared_info.virt = NULL; + + pg = mfn_to_page(d->shared_info.mfn); + + put_page_alloc_ref(pg); + put_page_and_type(pg); } /* diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c index e86e2bfab0..a17422284d 100644 --- a/xen/common/event_channel.c +++ b/xen/common/event_channel.c @@ -1325,6 +1325,9 @@ void evtchn_destroy(struct domain *d) { unsigned int i; + /* This must be done before shared_info is freed */ + BUG_ON(!d->shared_info.virt); + /* After this barrier no new event-channel allocations can occur. */ BUG_ON(!d->is_dying); spin_barrier(&d->event_lock); diff --git a/xen/common/time.c b/xen/common/time.c index 58fa9abc40..ada02faf07 100644 --- a/xen/common/time.c +++ b/xen/common/time.c @@ -99,6 +99,18 @@ void update_domain_wallclock_time(struct domain *d) uint32_t *wc_version; uint64_t sec; + if ( d != current->domain ) + { + /* + * We need to check is_dying here as, if it is set, the + * shared_info may have been freed. To do this safely we need + * hold the domain lock. + */ + domain_lock(d); + if ( d->is_dying ) + goto unlock; + } + spin_lock(&wc_lock); wc_version = &shared_info(d, wc_version); @@ -121,6 +133,9 @@ void update_domain_wallclock_time(struct domain *d) *wc_version = version_update_end(*wc_version); spin_unlock(&wc_lock); + unlock: + if ( d != current->domain ) + domain_unlock(d); } /* Set clock to after 00:00:00 UTC, 1 January, 1970. */