From: James Hogan <james.hogan@imgtec.com> To: <linux-mips@linux-mips.org> Cc: "Paolo Bonzini" <pbonzini@redhat.com>, "Radim Krčmář" <rkrcmar@redhat.com>, "Ralf Baechle" <ralf@linux-mips.org>, kvm@vger.kernel.org, stable@vger.kernel.org, "James Hogan" <james.hogan@imgtec.com> Subject: [PATCH 2/3] KVM: MIPS: Make ERET handle ERL before EXL Date: Tue, 25 Oct 2016 16:11:11 +0100 [thread overview] Message-ID: <bffcf699b742d3cb02aa26438fcd361f8a0ab110.1477320903.git-series.james.hogan@imgtec.com> (raw) In-Reply-To: <cover.c0ced53ae71e1272ec1aaa16007e9eebb1c0eac6.1477320903.git-series.james.hogan@imgtec.com> 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 <james.hogan@imgtec.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Radim Krčmář" <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Cc: <stable@vger.kernel.org> # 3.10.x- --- arch/mips/kvm/emulate.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index 8770f32c9e0b..c45ef0f13dfa 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -790,15 +790,15 @@ 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); -- git-series 0.8.10
WARNING: multiple messages have this Message-ID (diff)
From: James Hogan <james.hogan@imgtec.com> To: linux-mips@linux-mips.org Cc: "Paolo Bonzini" <pbonzini@redhat.com>, "Radim Krčmář" <rkrcmar@redhat.com>, "Ralf Baechle" <ralf@linux-mips.org>, kvm@vger.kernel.org, stable@vger.kernel.org, "James Hogan" <james.hogan@imgtec.com> Subject: [PATCH 2/3] KVM: MIPS: Make ERET handle ERL before EXL Date: Tue, 25 Oct 2016 16:11:11 +0100 [thread overview] Message-ID: <bffcf699b742d3cb02aa26438fcd361f8a0ab110.1477320903.git-series.james.hogan@imgtec.com> (raw) Message-ID: <20161025151111.MYnKxDruENxsyxVHujIFl6iIIVvkgkHDQcj4CDL0MVs@z> (raw) In-Reply-To: <cover.c0ced53ae71e1272ec1aaa16007e9eebb1c0eac6.1477320903.git-series.james.hogan@imgtec.com> 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 <james.hogan@imgtec.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Radim Krčmář" <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Cc: <stable@vger.kernel.org> # 3.10.x- --- arch/mips/kvm/emulate.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index 8770f32c9e0b..c45ef0f13dfa 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -790,15 +790,15 @@ 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); -- git-series 0.8.10
next prev parent reply other threads:[~2016-10-25 15:11 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-10-25 15:08 [PATCH 0/3] KVM: MIPS: Miscellaneous 4.9 fixes James Hogan 2016-10-25 15:08 ` James Hogan 2016-10-25 15:08 ` [PATCH 1/3] KVM: MIPS: Fix lazy user ASID regenerate for SMP James Hogan 2016-10-25 15:08 ` James Hogan 2016-10-25 15:11 ` James Hogan [this message] 2016-10-25 15:11 ` [PATCH 2/3] KVM: MIPS: Make ERET handle ERL before EXL James Hogan 2016-10-25 15:11 ` [PATCH 3/3] KVM: MIPS: Precalculate MMIO load resume PC James Hogan 2016-10-25 15:11 ` James Hogan 2016-10-25 15:57 ` [PATCH 0/3] KVM: MIPS: Miscellaneous 4.9 fixes Paolo Bonzini
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