From f3a8603f098fd2c68311d945a6531d1e3b62271c Mon Sep 17 00:00:00 2001 From: James Hogan Date: Fri, 7 Oct 2016 22:01:05 +0100 Subject: [PATCH] KVM: MIPS/TLB: Fix off-by-one in TLB invalidate MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit kvm_mips_host_tlb_inv() uses the TLBP instruction to probe the host TLB for an entry matching the given guest virtual address, and determines whether a match was found based on whether CP0_Index > 0. This is technically incorrect as an index of 0 (with the high bit clear) is a perfectly valid TLB index. This is harmless at the moment due to the use of at least 1 wired TLB entry for the KVM commpage, however we will soon be ridding ourselves of that particular wired entry so lets fix the condition in case the entry needing invalidation does land at TLB index 0. Signed-off-by: James Hogan Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org --- arch/mips/kvm/tlb.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c index 6c1f894b8754..4bf82613d440 100644 --- a/arch/mips/kvm/tlb.c +++ b/arch/mips/kvm/tlb.c @@ -282,7 +282,7 @@ int kvm_mips_host_tlb_inv(struct kvm_vcpu *vcpu, unsigned long va) if (idx >= current_cpu_data.tlbsize) BUG(); - if (idx > 0) { + if (idx >= 0) { write_c0_entryhi(UNIQUE_ENTRYHI(idx)); write_c0_entrylo0(0); write_c0_entrylo1(0); @@ -297,7 +297,7 @@ int kvm_mips_host_tlb_inv(struct kvm_vcpu *vcpu, unsigned long va) local_irq_restore(flags); - if (idx > 0) + if (idx >= 0) kvm_debug("%s: Invalidated entryhi %#lx @ idx %d\n", __func__, (va & VPN2_MASK) | kvm_mips_get_user_asid(vcpu), idx); -- 2.20.1