From patchwork Thu May 10 09:49:24 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: KVM: PPC: Book3S HV: Fix bug leading to deadlock in guest HPT updates From: Paul Mackerras X-Patchwork-Id: 158236 Message-Id: <20120510094924.GA16271@bloggs.ozlabs.ibm.com> To: Alexander Graf , Avi Kivity Cc: kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Date: Thu, 10 May 2012 19:49:24 +1000 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 --- arch/powerpc/kvm/book3s_hv_rm_mmu.c | 1 + 1 file changed, 1 insertion(+) 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; }