This patch fixes a severe bug in vtlb, where domU may face machine crash

intermittently. Normally in page fault handler, the entry hit in vtlb shouldn't
be injected back to vtlb again, not to say meaningless -1UL. After this fix,
vtlb hit ratio also improves since guest svhpt entry may live longer.

Signed-off-by Kevin Tian <kevin.tian@intel.com>

diff --git a/xen/arch/ia64/xen/vcpu.c b/xen/arch/ia64/xen/vcpu.c
index 8e846112f5c03f7686ffe1a5bb86b819a5bcbe9b..bbf59c579e7b4b0b930945b3bf239c4d66b18cb0 100644 (file)
--- a/xen/arch/ia64/xen/vcpu.c
+++ b/xen/arch/ia64/xen/vcpu.c
@@ -1721,7 +1721,7 @@ void vcpu_itc_no_srlz(VCPU *vcpu, UINT64 IorD, UINT64 vaddr, UINT64 pte, UINT64
        // PAGE_SIZE mapping in the vhpt for now, else purging is complicated
        else vhpt_insert(vaddr,pte,PAGE_SHIFT<<2);
 #endif
-       if (IorD & 0x4) return;  // don't place in 1-entry TLB
+       if ((mp_pte == -1UL) || (IorD & 0x4)) return;  // don't place in 1-entry TLB
        if (IorD & 0x1) {
                vcpu_set_tr_entry(&PSCBX(vcpu,itlb),pte,ps<<2,vaddr);
                PSCBX(vcpu,itlb_pte) = mp_pte;