lkml.org 
[lkml]   [2015]   [Jul]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 4/6] xen/x86/pvh: Set up descriptors for 32-bit PVH guests
    On Mon, Jul 06, 2015 at 11:34:23PM -0400, Boris Ostrovsky wrote:
    > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    > ---
    > arch/x86/xen/enlighten.c | 16 ++++++++++++----
    > 1 file changed, 12 insertions(+), 4 deletions(-)
    >
    > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
    > index 0b95c9b..7953e68 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;
    >
    > - load_percpu_segment(cpu); /* We need to access per-cpu area */
    > + setup_stack_canary_segment(cpu);
    > 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 +1392,16 @@ static void __ref xen_setup_gdt(int cpu)
    > loadsegment(ds, 0);
    > loadsegment(fs, 0);
    > #else
    > - /* PVH: TODO Implement. */
    > - BUG();
    > + asm volatile ("ljmp %1,$1f\n"
    > + "1:\n"
    > + "movl %2,%0\n"
    > + "movl %0,%%ss\n"
    > + "movl %3,%0\n"
    > + "movl %0,%%ds\n"
    > + "movl %0,%%es\n"
    > + : "=&r" (dummy)
    > + : "i" (__KERNEL_CS), "i" (__KERNEL_DS),
    > + "i" (__USER_DS));
    > #endif

    Which comes out to:
    ljmp $96,$1f #[KERNEL_CS]
    1:
    movl $104,%eax #, dummy #[KERNEL_DS]
    movl %eax,%ss # dummy
    movl $123,%eax #, dummy #[USER_DS]
    movl %eax,%ds # dummy
    movl %eax,%es # dummy

    And that looks right

    Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

    > return; /* PVH does not need any PV GDT ops. */
    > }
    > --
    > 1.8.1.4
    >


    \
     
     \ /
      Last update: 2015-07-07 22:01    [W:6.573 / U:0.320 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site