From 6df82a7b88dc9b0b519765562b005ef9196d812a Mon Sep 17 00:00:00 2001 From: James Hogan Date: Thu, 9 Jun 2016 10:50:46 +0100 Subject: [PATCH] MIPS: KVM: Fix CACHE triggered exception emulation MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When emulating TLB miss / invalid exceptions during CACHE instruction emulation, be sure to set up the correct PC and host_cp0_badvaddr state for the kvm_mips_emlulate_tlb*_ld() function to pick up for guest EPC and BadVAddr. PC needs to be rewound otherwise the guest EPC will end up pointing at the next instruction after the faulting CACHE instruction. host_cp0_badvaddr must be set because guest CACHE instructions trap with a Coprocessor Unusable exception, which doesn't update the host BadVAddr as a TLB exception would. This doesn't tend to get hit when dynamic translation of emulated instructions is enabled, since only the first execution of each CACHE instruction actually goes through this code path, with subsequent executions hitting the SYNCI instruction that it gets replaced with. Signed-off-by: James Hogan Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Ralf Baechle Cc: kvm@vger.kernel.org Cc: linux-mips@linux-mips.org Signed-off-by: Paolo Bonzini --- arch/mips/kvm/emulate.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index 52bec0fe2fbb..645c8a1982a7 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -1636,6 +1636,7 @@ enum emulation_result kvm_mips_emulate_cache(uint32_t inst, uint32_t *opc, if (index < 0) { vcpu->arch.host_cp0_entryhi = (va & VPN2_MASK); vcpu->arch.host_cp0_badvaddr = va; + vcpu->arch.pc = curr_pc; er = kvm_mips_emulate_tlbmiss_ld(cause, NULL, run, vcpu); preempt_enable(); @@ -1647,6 +1648,8 @@ enum emulation_result kvm_mips_emulate_cache(uint32_t inst, uint32_t *opc, * invalid exception to the guest */ if (!TLB_IS_VALID(*tlb, va)) { + vcpu->arch.host_cp0_badvaddr = va; + vcpu->arch.pc = curr_pc; er = kvm_mips_emulate_tlbinv_ld(cause, NULL, run, vcpu); preempt_enable(); -- 2.20.1