[Xen-changelog] [xen-unstable] [IA64] fix RSE issues rlated to handle_lazy_cover().

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User awilliam@xxxxxxxxxxx
# Node ID 795d31772505ac8f951a70c1ef39aaa09cda7f47
# Parent  a9c1e614c9ffb2e1a0dec812663786ac6b4bdf77
[IA64] fix RSE issues rlated to handle_lazy_cover().

It must be after trying vTLB in ia64_do_page_fault().

This patch fixes the following scenario.

linux-2.6-xen-sparse/arch/ia64/xen/xenentry.S
Here psr.i and psr.ic is off
rse_clear_invalid:
...
(pRecurse) br.call.dptk.few b0=rse_clear_invalid
        ;;
        mov loc8=0
        mov loc9=0

1. Right before mov loc8=0, vcpu is switched to another cpu.
2. While the vcpu is waiting for cpu, the tlb entry which backs the rse
   stack is purged.
3. The vcpu gets cpu again, tlb miss fault occurs with isr.ir = 1.
4. xen ia64_do_page_fault() calls handle_lazy_cover() which sets
   cr.ifs = 0.
5. xen returns cpu execution to the guest.
6. mov loc8 = 0 is executed with cfm = 0.
   Illigal operation fault is raised 
7. priv_handle_op() is called. but it fails to emulate because
   mov loc8 = 0 isn't privileged op.
8. ia64_handle_privop() calls panic_domain().

Signed-off-by: Xu, Anthony <anthony.xu@xxxxxxxxx>
Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
---
 xen/arch/ia64/xen/faults.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletion(-)

diff -r a9c1e614c9ff -r 795d31772505 xen/arch/ia64/xen/faults.c
--- a/xen/arch/ia64/xen/faults.c        Fri Jun 23 15:20:43 2006 -0600
+++ b/xen/arch/ia64/xen/faults.c        Fri Jun 23 15:24:06 2006 -0600
@@ -218,7 +218,6 @@ void ia64_do_page_fault (unsigned long a
        int is_ptc_l_needed = 0;
        u64 logps;
 
-       if ((isr & IA64_ISR_IR) && handle_lazy_cover(current, regs)) return;
        if ((isr & IA64_ISR_SP)
            || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == 
IA64_ISR_CODE_LFETCH))
        {
@@ -269,6 +268,10 @@ void ia64_do_page_fault (unsigned long a
                }
                return;
        }
+
+       if ((isr & IA64_ISR_IR) && handle_lazy_cover(current, regs))
+               return;
+
        if (!PSCB(current,interrupt_collection_enabled)) {
                check_bad_nested_interruption(isr,regs,fault);
                //printf("Delivering NESTED DATA TLB fault\n");

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