From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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
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 [thread overview]
Message-ID: <55A920FD.6050101__24884.6089853489$1437147509$gmane$org@oracle.com> (raw)
In-Reply-To: <20150717152113.GB18085@l.oracle.com>
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 <boris.ostrovsky@oracle.com>
>> ---
>> 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
>>
next prev parent reply other threads:[~2015-07-17 15:37 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-16 21:43 [PATCH v2 0/6] 32-bit PVH domU support Boris Ostrovsky
2015-07-16 21:43 ` [PATCH v2 1/6] xen/x86/pvh: Save %rbx in xen_pvh_early_cpu_init() Boris Ostrovsky
2015-07-16 21:43 ` [PATCH v2 2/6] xen/x86: Remove unnecessary memset() call Boris Ostrovsky
2015-07-16 21:43 ` [PATCH v2 3/6] xen/x86/pvh: Properly set page tables for 32-bit PVH guests Boris Ostrovsky
2015-07-16 21:43 ` [PATCH v2 4/6] xen/x86/pvh: Set up descriptors " Boris Ostrovsky
2015-07-17 15:21 ` Konrad Rzeszutek Wilk
[not found] ` <20150717152113.GB18085@l.oracle.com>
2015-07-17 15:36 ` Boris Ostrovsky [this message]
[not found] ` <55A920FD.6050101@oracle.com>
2015-07-17 16:43 ` Konrad Rzeszutek Wilk
[not found] ` <20150717164331.GA19827@l.oracle.com>
2015-07-17 17:52 ` Boris Ostrovsky
[not found] ` <55A940CC.6090509@oracle.com>
2015-07-21 15:32 ` Boris Ostrovsky
2015-07-16 21:43 ` [PATCH v2 5/6] xen/x86/pvh: Add 32-bit PVH initialization code Boris Ostrovsky
2015-07-16 21:43 ` [PATCH v2 6/6] xen/x86/pvh: Allow building 32-bit PVH guests Boris Ostrovsky
[not found] ` <1437083021-24488-2-git-send-email-boris.ostrovsky@oracle.com>
2015-07-17 15:09 ` [PATCH v2 1/6] xen/x86/pvh: Save %rbx in xen_pvh_early_cpu_init() Konrad Rzeszutek Wilk
[not found] ` <1437083021-24488-6-git-send-email-boris.ostrovsky@oracle.com>
2015-07-17 15:21 ` [PATCH v2 5/6] xen/x86/pvh: Add 32-bit PVH initialization code Konrad Rzeszutek Wilk
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