From: James Hogan Date: Tue, 25 Oct 2016 15:11:11 +0000 (+0100) Subject: KVM: MIPS: Make ERET handle ERL before EXL X-Git-Tag: v4.1.36~16 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b05ff0cb0dea33b12e803e5bf2bb66a382c8696b;p=platform%2Fkernel%2Flinux-exynos.git KVM: MIPS: Make ERET handle ERL before EXL [ Upstream commit ede5f3e7b54a4347be4d8525269eae50902bd7cd ] The ERET instruction to return from exception is used for returning from exception level (Status.EXL) and error level (Status.ERL). If both bits are set however we should be returning from ERL first, as ERL can interrupt EXL, for example when an NMI is taken. KVM however checks EXL first. Fix the order of the checks to match the pseudocode in the instruction set manual. Fixes: e685c689f3a8 ("KVM/MIPS32: Privileged instruction/target branch emulation.") 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 Cc: # 3.10.x- Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index d6476d11212e..ef4fbeb3d6d3 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -752,15 +752,15 @@ enum emulation_result kvm_mips_emul_eret(struct kvm_vcpu *vcpu) struct mips_coproc *cop0 = vcpu->arch.cop0; enum emulation_result er = EMULATE_DONE; - if (kvm_read_c0_guest_status(cop0) & ST0_EXL) { + if (kvm_read_c0_guest_status(cop0) & ST0_ERL) { + kvm_clear_c0_guest_status(cop0, ST0_ERL); + vcpu->arch.pc = kvm_read_c0_guest_errorepc(cop0); + } else if (kvm_read_c0_guest_status(cop0) & ST0_EXL) { kvm_debug("[%#lx] ERET to %#lx\n", vcpu->arch.pc, kvm_read_c0_guest_epc(cop0)); kvm_clear_c0_guest_status(cop0, ST0_EXL); vcpu->arch.pc = kvm_read_c0_guest_epc(cop0); - } else if (kvm_read_c0_guest_status(cop0) & ST0_ERL) { - kvm_clear_c0_guest_status(cop0, ST0_ERL); - vcpu->arch.pc = kvm_read_c0_guest_errorepc(cop0); } else { kvm_err("[%#lx] ERET when MIPS_SR_EXL|MIPS_SR_ERL == 0\n", vcpu->arch.pc);