# HG changeset patch
# User Alex Williamson <alex.williamson@xxxxxx>
# Date 1180987422 21600
# Node ID e7295db8866483a34afd6e9226cfa2757b8492fa
# Parent 249446c52deba48aaaa2255535edf5da204379d4
[IA64] Prevent rfi emulation with double un-cover
Recently (CS 13436) rfi hyperprivop was simplified. But as a consequence
rfi emulation with double un-cover is not possible anymore.
Comment priv_rfi and forbid rfi emulation with double un-cover.
Signed-off-by: Tristan Gingold <tgingold@xxxxxxx>
---
xen/arch/ia64/xen/hyperprivop.S | 18 ++++++++++++++++--
xen/arch/ia64/xen/privop.c | 9 +++++++++
2 files changed, 25 insertions(+), 2 deletions(-)
diff -r 249446c52deb -r e7295db88664 xen/arch/ia64/xen/hyperprivop.S
--- a/xen/arch/ia64/xen/hyperprivop.S Mon Jun 04 14:00:35 2007 -0600
+++ b/xen/arch/ia64/xen/hyperprivop.S Mon Jun 04 14:03:42 2007 -0600
@@ -1029,8 +1029,22 @@ ENTRY(slow_vcpu_rfi)
ld8 r22=[r22];;
tbit.z p6,p0=r22,63
(p6) br.spnt.few dispatch_break_fault ;;
- // if vips is valid, discard current register frame
- // don't need dorfirfi any more
+ // If vifs.v is set, we have two IFS to consider:
+ // * the guest IFS
+ // * the hypervisor IFS (validated by cover)
+ // Because IFS is copied to CFM and is used to adjust AR.BSP,
+ // virtualization of rfi is not easy.
+ // Previously there was a two steps method (a first rfi jumped to
+ // a stub which performed a new rfi).
+ // This new method discards the RS before executing the hypervisor
+ // cover. After cover, IFS.IFM will be zero. This IFS would simply
+ // clear CFM but not modifying AR.BSP. Therefore the guest IFS can
+ // be used instead and there is no need of a second rfi.
+ // Discarding the RS with the following alloc instruction just clears
+ // CFM, which is safe because rfi will overwrite it.
+ // There is a drawback: because the RS must be discarded before
+ // executing C code, emulation of rfi must go through an hyperprivop
+ // and not through normal instruction decoding.
alloc r22=ar.pfs,0,0,0,0
br.spnt.few dispatch_break_fault
;;
diff -r 249446c52deb -r e7295db88664 xen/arch/ia64/xen/privop.c
--- a/xen/arch/ia64/xen/privop.c Mon Jun 04 14:00:35 2007 -0600
+++ b/xen/arch/ia64/xen/privop.c Mon Jun 04 14:03:42 2007 -0600
@@ -31,6 +31,15 @@ Privileged operation emulation routines
static IA64FAULT priv_rfi(VCPU * vcpu, INST64 inst)
{
+ REGS *regs = vcpu_regs(vcpu);
+ if (PSCB(vcpu, ifs) > 0x8000000000000000UL
+ && regs->cr_ifs > 0x8000000000000000UL) {
+ panic_domain(regs,
+ "rfi emulation with double uncover is "
+ "impossible - use hyperprivop\n"
+ " ip=0x%lx vifs=0x%lx ifs=0x%lx\n",
+ regs->cr_iip, PSCB(vcpu, ifs), regs->cr_ifs);
+ }
return vcpu_rfi(vcpu);
}
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