Messages in this thread | | | Date | Tue, 15 Jul 2014 15:00:56 -0400 | From | Boris Ostrovsky <> | Subject | Re: [RFC PATCH] x86_64,entry,xen: Do not invoke espfix64 on Xen |
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On 07/15/2014 01:22 PM, Andy Lutomirski wrote: > On Tue, Jul 15, 2014 at 10:19 AM, Boris Ostrovsky > <boris.ostrovsky@oracle.com> wrote: >> On 07/15/2014 12:23 PM, Andy Lutomirski wrote: >>> >>> diff --git a/arch/x86/kernel/paravirt_patch_64.c >>> b/arch/x86/kernel/paravirt_patch_64.c >>> index 3f08f34..a1da673 100644 >>> --- a/arch/x86/kernel/paravirt_patch_64.c >>> +++ b/arch/x86/kernel/paravirt_patch_64.c >>> @@ -6,7 +6,6 @@ DEF_NATIVE(pv_irq_ops, irq_disable, "cli"); >>> DEF_NATIVE(pv_irq_ops, irq_enable, "sti"); >>> DEF_NATIVE(pv_irq_ops, restore_fl, "pushq %rdi; popfq"); >>> DEF_NATIVE(pv_irq_ops, save_fl, "pushfq; popq %rax"); >>> -DEF_NATIVE(pv_cpu_ops, iret, "iretq"); >>> DEF_NATIVE(pv_mmu_ops, read_cr2, "movq %cr2, %rax"); >>> DEF_NATIVE(pv_mmu_ops, read_cr3, "movq %cr3, %rax"); >>> DEF_NATIVE(pv_mmu_ops, write_cr3, "movq %rdi, %cr3"); >>> @@ -50,7 +49,6 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf, >>> PATCH_SITE(pv_irq_ops, save_fl); >>> PATCH_SITE(pv_irq_ops, irq_enable); >>> PATCH_SITE(pv_irq_ops, irq_disable); >>> - PATCH_SITE(pv_cpu_ops, iret); >> >> >> Does this mean that we are no longer patching IRET with a jump to a >> hypercall? >> > IIUC this means that, on native, we are no longer patching > INTERRUPT_RETURN with an "iretq" instruction, so INTERRUPT_RETURN will > remain a "jmp native_iret". I'm not sure why this patch was there in > the first place. On Xen, it should still get patched with the > hypercall (although someone should verify this).
Right, I missed the fact that this is native_patch.
I did some light testing and it appears to work. Are you targeting this for 3.16?
One way or the other we need to disable espfix64 on PV --- I discovered that one of Peter's tests crashes the hypervisor.
-boris
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