[Xen-changelog] [IA64] tlb miss fix

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

# HG changeset patch
# User awilliam@xxxxxxxxxxx
# Node ID f94931b07c67327d5cd983cc10c37976f4bb6236
# Parent  5de0ee4ae76bcf70a08c063b5936fc6ffe2733b4
[IA64] tlb miss fix

make dtlb miss handler to handle xen/ia64 identity mapping area.
xen/ia64 enables vhpt walker for all regions unlink Linux.
So dtlb misses on identity mapping area are catched by
dtlb miss handler, not alt dltb miss handler.

- dtlb miss on identity mapping area must be handled
- alt dtlb miss must be handled
- itlb miss on the identity mapping area must not occur
  panic via page_fault().
- alt itlb miss by a guest must be handled
  it occurs during dom0 boot.
- alt itlb miss by xen must not occur
  panic by FORCE_CRASH

vmx_ivt.S already has such tweaks by checking psr.vm bit.

TODO: optimization
      dtlb miss handlers are performance critical so that
      it should be heavily optimized like alt_dtlb_miss.

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>

diff -r 5de0ee4ae76b -r f94931b07c67 xen/arch/ia64/xen/ivt.S
--- a/xen/arch/ia64/xen/ivt.S   Fri Feb 24 15:29:52 2006
+++ b/xen/arch/ia64/xen/ivt.S   Fri Feb 24 15:34:11 2006
@@ -298,12 +298,83 @@
        DBG_FAULT(2)
 #ifdef XEN
        VHPT_CCHAIN_LOOKUP(dtlb_miss,d)
+#if VHPT_ENABLED
+       // XXX TODO optimization
+       mov r31=pr                              // save predicates
+       mov r30=cr.ipsr
+       mov r28=cr.iip                  
+       mov r16=cr.ifa                          // get virtual address
+       mov r17=cr.isr                          // save predicates
+       ;;
+
+       extr.u r18 = r30, IA64_PSR_CPL0_BIT, 2  // extract psr.cpl
+       ;; 
+       cmp.ne p6, p0 = r0, r18                 // cpl == 0?
+(p6)   br.cond.sptk 2f
+
+       // is speculation bit on?
+       tbit.nz p7,p0=r17,IA64_ISR_SP_BIT       
+       ;; 
+(p7)   br.cond.spnt 2f
+
+       // is non-access bit on?
+       tbit.nz p8,p0=r17,IA64_ISR_NA_BIT       
+       ;;
+(p8)   br.cond.spnt 2f
+
+       // cr.isr.code == IA64_ISR_CODE_LFETCH?
+       and r18=IA64_ISR_CODE_MASK,r17          // get the isr.code field
+       ;; 
+       cmp.eq p9,p0=IA64_ISR_CODE_LFETCH,r18   // check isr.code field
+(p9)   br.cond.spnt 2f
+
+       // Is the faulted iip in vmm area?
+       // check [59:58] bit
+       // 00, 11: guest
+       // 01, 10: vmm
+       extr.u r19 = r28, 58, 2
+       ;; 
+       cmp.eq p10, p0 = 0x0, r19
+(p10)  br.cond.sptk 2f
+       cmp.eq p11, p0 = 0x3, r19
+(p11)  br.cond.sptk 2f
+
+       // Is the faulted address is in the identity mapping area?
+       // 0xf000... or 0xe8000...
+       extr.u r20 = r16, 59, 5
+       ;; 
+       cmp.eq p12, p0 = 0x1e, r20 // (0xf0 >> 3) = 0x1e
+(p12)  br.cond.spnt 1f
+       cmp.eq p0, p13 = 0x1d, r20 // (0xe8 >> 3) = 0x1d
+(p13)  br.cond.sptk 2f
+
+1:
+       // xen identity mappin area.
+       movl r24=PAGE_KERNEL
+       movl r25=(((1 << IA64_MAX_PHYS_BITS) - 1) & ~0xfff)
+       ;;
+       shr.u r26=r16,55        // move address bit 59 to bit 4
+       and r25=r25,r16         // clear ed, reserved bits, and PTE control bits
+       ;;
+       and r26=0x10,r26        // bit 4=address-bit(59)
+       ;; 
+       or r25=r25,r24          // insert PTE control bits into r25
+       ;;
+       or r25=r25,r26          // set bit 4 (uncached) if the access was to 
region 6
+       ;;
+       itc.d r25               // insert the TLB entry
+       mov pr=r31,-1
+       rfi
+
+2:
+#endif 
 #ifdef VHPT_GLOBAL
 //     br.cond.sptk page_fault
        br.cond.sptk fast_tlb_miss_reflect
        ;;
 #endif
-#endif
+       mov r29=b0                              // save b0
+#else  
        /*
         * The DTLB handler accesses the L3 PTE via the virtually mapped linear
         * page table.  If a nested TLB miss occurs, we switch into physical
@@ -313,6 +384,7 @@
        mov r16=cr.ifa                          // get virtual address
        mov r29=b0                              // save b0
        mov r31=pr                              // save predicates
+#endif
 dtlb_fault:
        mov r17=cr.iha                          // get virtual address of L3 PTE
        movl r30=1f                             // load nested fault 
continuation point
@@ -399,6 +471,9 @@
        ;;
        or r19=r19,r18          // set bit 4 (uncached) if the access was to 
region 6
 (p8)   br.cond.spnt page_fault
+#ifdef XEN
+       FORCE_CRASH
+#endif 
        ;;
        itc.i r19               // insert the TLB entry
        mov pr=r31,-1
diff -r 5de0ee4ae76b -r f94931b07c67 xen/include/asm-ia64/config.h
--- a/xen/include/asm-ia64/config.h     Fri Feb 24 15:29:52 2006
+++ b/xen/include/asm-ia64/config.h     Fri Feb 24 15:34:11 2006
@@ -251,8 +251,6 @@
 #define seq_printf(a,b...) printf(b)
 #define CONFIG_BLK_DEV_INITRD // needed to reserve memory for domain0
 
-#define FORCE_CRASH()  asm("break 0;;");
-
 void dummy_called(char *function);
 #define dummy()        dummy_called(__FUNCTION__)
 
@@ -301,6 +299,9 @@
 
 #ifndef __ASSEMBLY__
 #include <linux/linkage.h>
+#define FORCE_CRASH()  asm("break.m 0;;");
+#else
+#define FORCE_CRASH    break.m 0;;
 #endif
 
 #endif /* _IA64_CONFIG_H_ */

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