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KVM: PPC: Book3S HV: Fix incorrect branch in H_CEDE code
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In handling the H_CEDE hypercall, if this vcpu has already been
prodded (with the H_PROD hypercall, which Linux guests don't in fact
use), we branch to a numeric label '1f'.  Unfortunately there is
another '1:' label before the one that we want to jump to.  This fixes
the problem by using a textual label, 'kvm_cede_prodded'.  It also
changes the label for another longish branch from '2:' to
'kvm_cede_exit' to avoid a possible future problem if code modifications
add another numeric '2:' label in between.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
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Paul Mackerras authored and Alexander Graf committed Aug 16, 2012
1 parent 439793d commit 04f995a
Showing 1 changed file with 7 additions and 5 deletions.
12 changes: 7 additions & 5 deletions arch/powerpc/kvm/book3s_hv_rmhandlers.S
Original file line number Diff line number Diff line change
Expand Up @@ -1421,13 +1421,13 @@ _GLOBAL(kvmppc_h_cede)
sync /* order setting ceded vs. testing prodded */
lbz r5,VCPU_PRODDED(r3)
cmpwi r5,0
bne 1f
bne kvm_cede_prodded
li r0,0 /* set trap to 0 to say hcall is handled */
stw r0,VCPU_TRAP(r3)
li r0,H_SUCCESS
std r0,VCPU_GPR(R3)(r3)
BEGIN_FTR_SECTION
b 2f /* just send it up to host on 970 */
b kvm_cede_exit /* just send it up to host on 970 */
END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206)

/*
Expand All @@ -1446,7 +1446,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206)
or r4,r4,r0
PPC_POPCNTW(R7,R4)
cmpw r7,r8
bge 2f
bge kvm_cede_exit
stwcx. r4,0,r6
bne 31b
li r0,1
Expand Down Expand Up @@ -1555,15 +1555,17 @@ kvm_end_cede:
b hcall_real_fallback

/* cede when already previously prodded case */
1: li r0,0
kvm_cede_prodded:
li r0,0
stb r0,VCPU_PRODDED(r3)
sync /* order testing prodded vs. clearing ceded */
stb r0,VCPU_CEDED(r3)
li r3,H_SUCCESS
blr

/* we've ceded but we want to give control to the host */
2: li r3,H_TOO_HARD
kvm_cede_exit:
li r3,H_TOO_HARD
blr

secondary_too_late:
Expand Down

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