From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Ostrovsky Subject: Re: [PATCH v2 4/6] xen/x86/pvh: Set up descriptors for 32-bit PVH guests Date: Fri, 17 Jul 2015 11:36:29 -0400 Message-ID: <55A920FD.6050101__24884.6089853489$1437147509$gmane$org@oracle.com> References: <1437083021-24488-1-git-send-email-boris.ostrovsky@oracle.com> <1437083021-24488-5-git-send-email-boris.ostrovsky@oracle.com> <20150717152113.GB18085@l.oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1ZG7h7-0007bD-H7 for xen-devel@lists.xenproject.org; Fri, 17 Jul 2015 15:37:01 +0000 In-Reply-To: <20150717152113.GB18085@l.oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Konrad Rzeszutek Wilk Cc: elena.ufimtseva@oracle.com, ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com, andrew.cooper3@citrix.com, tim@xen.org, linux-kernel@vger.kernel.org, david.vrabel@citrix.com, jbeulich@suse.com, xen-devel@lists.xenproject.org, ian.jackson@eu.citrix.com, roger.pau@citrix.com List-Id: xen-devel@lists.xenproject.org On 07/17/2015 11:21 AM, Konrad Rzeszutek Wilk wrote: > On Thu, Jul 16, 2015 at 05:43:39PM -0400, Boris Ostrovsky wrote: >> Signed-off-by: Boris Ostrovsky >> --- >> Changes in v2: >> * Set segment selectors using loadsegment() instead of assembly >> >> arch/x86/xen/enlighten.c | 15 ++++++++++----- >> 1 file changed, 10 insertions(+), 5 deletions(-) >> >> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c >> index f8dc398..d665b1d 100644 >> --- a/arch/x86/xen/enlighten.c >> +++ b/arch/x86/xen/enlighten.c >> @@ -1362,12 +1362,12 @@ static void __init xen_boot_params_init_edd(void) >> static void __ref xen_setup_gdt(int cpu) >> { >> if (xen_feature(XENFEAT_auto_translated_physmap)) { >> -#ifdef CONFIG_X86_64 >> - unsigned long dummy; >> + unsigned long __attribute__((unused)) dummy; >> >> - load_percpu_segment(cpu); /* We need to access per-cpu area */ > You removed that - where are we going to do that? As the > 'switch_to_new_gdt' uses the per-cpu GDT table. load_percpu_segment() is part of switch_to_new_gdt(), so I thought there is no need to call it here. But you are right --- switch_to_new_gdt() starts with get_cpu_gdt_table() which accesses per-CPU area. How did this manage to work then? > >> + setup_stack_canary_segment(cpu); > As this one too ? This one I added. On 64-bit it's a nop so we never had problems without having this call. On 32-bit, if CC_STACKPROTECTOR is set, we will fail without setting this up. -boris >> switch_to_new_gdt(cpu); /* GDT and GS set */ >> >> +#ifdef CONFIG_X86_64 >> /* We are switching of the Xen provided GDT to our HVM mode >> * GDT. The new GDT has __KERNEL_CS with CS.L = 1 >> * and we are jumping to reload it. >> @@ -1392,8 +1392,13 @@ static void __ref xen_setup_gdt(int cpu) >> loadsegment(ds, 0); >> loadsegment(fs, 0); >> #else >> - /* PVH: TODO Implement. */ >> - BUG(); >> + asm volatile ("ljmp %0,$1f\n" >> + "1:\n" >> + :: "i" (__KERNEL_CS)); >> + >> + loadsegment(ss, __KERNEL_DS); >> + loadsegment(ds, __USER_DS); >> + loadsegment(es, __USER_DS); >> #endif >> return; /* PVH does not need any PV GDT ops. */ >> } >> -- >> 1.8.1.4 >>