This patch is not for commit. But for review, commnets.
Current itlb/dtlb miss handlers don't handle a tlb miss
in xen/ia64 identity mapping area.
Such a miss might occur because xen/ia64 enables vhpt walker
even for region 7. (Please see set_one_rr())
I haven't encountered it yet, I'm guessing so from reading code.
Vti itlb/dtlb miss handlers do it by checking psr.vm bits.
This patch is not so optimized for review,
but it should be done later.
# HG changeset patch
# User yamahata@xxxxxxxxxxxxx
# Node ID 07055de7ed1525110eefe5914847f0fc6002e232
# Parent cfa3b96b056debee0d86249bd74fb717b43ea84b
make itlb/dtlb miss handler to handle xen/ia64 identity mapping area.
xen/ia64 enables vhpt walker for all regions unlink Linux.
So tlb misses on identity mapping area are catched by
itlb/dtlb miss handler, not alt itlb/dltb miss handler.
vmx_ivt.S already has such tweaks by checking psr.vm bit.
TODO: optimization
tlb miss handlers are performance critical.
Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
diff -r cfa3b96b056d -r 07055de7ed15 xen/arch/ia64/xen/ivt.S
--- a/xen/arch/ia64/xen/ivt.S Fri Jan 13 14:58:41 2006 -0600
+++ b/xen/arch/ia64/xen/ivt.S Thu Jan 26 21:48:35 2006 +0900
@@ -245,12 +245,47 @@
DBG_FAULT(1)
#ifdef XEN
VHPT_CCHAIN_LOOKUP(itlb_miss,i)
+#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 1f
+
+ // 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 p7, p0 = 0x0, r19
+(p7) br.cond.sptk 1f
+ cmp.eq p8, p0 = 0x3, r19
+(p8) br.cond.sptk 1f
+
+ // Is the faulted address is in the identity mapping area?
+ // 0xf000... or 0xe8000...
+ extr.u r20 = r16, 59, 5
+ ;;
+ cmp.eq p9, p0 = 0x1e, r20 // (0xf0 >> 3) = 0x1e
+(p9) br.cond.spnt late_alt_itlb_miss
+ cmp.eq p10, p0 = 0x1d, r20 // (0xe8 >> 3) = 0x1d
+(p10) br.cond.spnt late_alt_itlb_miss
+1:
+#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 ITLB handler accesses the L3 PTE via the virtually mapped linear
* page table. If a nested TLB miss occurs, we switch into physical
@@ -260,6 +295,7 @@
mov r16=cr.ifa // get virtual address
mov r29=b0 // save b0
mov r31=pr // save predicates
+#endif
.itlb_fault:
mov r17=cr.iha // get virtual address of L3 PTE
movl r30=1f // load nested fault
continuation point
@@ -297,12 +333,47 @@
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 1f
+
+ // 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 p7, p0 = 0x0, r19
+(p7) br.cond.sptk 1f
+ cmp.eq p8, p0 = 0x3, r19
+(p8) br.cond.sptk 1f
+
+ // Is the faulted address is in the identity mapping area?
+ // 0xf000... or 0xe8000...
+ extr.u r20 = r16, 59, 5
+ ;;
+ cmp.eq p9, p0 = 0x1e, r20 // (0xf0 >> 3) = 0x1e
+(p9) br.cond.spnt late_alt_dtlb_miss
+ cmp.eq p10, p0 = 0x1d, r20 // (0xe8 >> 3) = 0x1d
+(p10) br.cond.spnt late_alt_dtlb_miss
+1:
+#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
@@ -312,6 +383,7 @@
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
--
yamahata
8603:07055de7ed15.patch
Description: Text document
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