Date: Tue, 18 Apr 2017 12:41:09 +0000 From: Dexuan Cui <decui@microsoft.com> To: Konstantin Belousov <kib@FreeBSD.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Cc: Sepherosa Ziehau <sephe@freebsd.org>, Hongjiang Zhang <honzhan@microsoft.com> Subject: RE: svn commit: r316767 - head/sys/amd64/amd64 Message-ID: <HK2P15301MB00033BEA7B656EBCD3BDFC5CBF190@HK2P15301MB0003.APCP153.PROD.OUTLOOK.COM> In-Reply-To: <201704131549.v3DFnt9I004050@repo.freebsd.org> References: <201704131549.v3DFnt9I004050@repo.freebsd.org>
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> From: owner-svn-src-head@freebsd.org [mailto:owner-svn-src- > head@freebsd.org] On Behalf Of Konstantin Belousov > Sent: Thursday, April 13, 2017 23:50 >=20 > Author: kib > Date: Thu Apr 13 15:49:55 2017 > New Revision: 316767 > URL: >=20 > Log: > Map DMAP as nx. >=20 > Demotions preserve PG_NX, so it is enough to set nx bit for initial > lowest-level paging entries. >=20 > Modified: > head/sys/amd64/amd64/pmap.c =20 Hi kib, Unluckily this patch breaks Hyper-V VM: In dev/hyperv/vmbus/hyperv.c: hypercall_create() we allocate one page and pass its physical address to the hypervisor, which initializes the page with executable code. Later in dev/hyperv/vmbus/hyperv.c: hypercall_post_message(), we "call" the executable code in the above page. Now with NX, the "call" gets a fault and as a result FreeBSD VM can't boot on Hyper-V. It looks memory allocated by bus_dmamem_alloc() and malloc() is not executable now. What else can we use? I guess we can only use contigmalloc() or kmem_malloc() to get a page that can be executable and use vtophys() to get its physical address? Looking forward to your suggestion! Thanks! -- Dexuan
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