Patchwork [5/5] KVM: PPC: Book3S HV: Fix bug leading to deadlock in guest HPT updates

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Submitter Alexander Graf
Date May 16, 2012, 1:05 p.m.
Message ID <1337173519-6780-6-git-send-email-agraf@suse.de>
Download mbox | patch
Permalink /patch/159629/
State New
Headers show

Comments

Alexander Graf - May 16, 2012, 1:05 p.m.
From: Paul Mackerras <paulus@samba.org>

When handling the H_BULK_REMOVE hypercall, we were forgetting to
invalidate and unlock the hashed page table entry (HPTE) in the case
where the page had been paged out.  This fixes it by clearing the
first doubleword of the HPTE in that case.

This fixes a regression introduced in commit a92bce95f0 ("KVM: PPC:
Book3S HV: Keep HPTE locked when invalidating").  The effect of the
regression is that the host kernel will sometimes hang when under
memory pressure.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
 arch/powerpc/kvm/book3s_hv_rm_mmu.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

Patch

diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index def880a..cec4dad 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -463,6 +463,7 @@  long kvmppc_h_bulk_remove(struct kvm_vcpu *vcpu)
 				/* insert R and C bits from PTE */
 				rcbits = rev->guest_rpte & (HPTE_R_R|HPTE_R_C);
 				args[j] |= rcbits << (56 - 5);
+				hp[0] = 0;
 				continue;
 			}