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Thu, 27 Jun 2024 18:03:50 +0000 (GMT) From: Gautam Menghani To: mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, naveen.n.rao@linux.ibm.com Cc: Gautam Menghani , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH 1/2] Revert "KVM: PPC: Book3S HV Nested: Stop forwarding all HFUs to L1" Date: Thu, 27 Jun 2024 23:33:35 +0530 Message-ID: <20240627180342.110238-2-gautam@linux.ibm.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240627180342.110238-1-gautam@linux.ibm.com> References: <20240627180342.110238-1-gautam@linux.ibm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: itJqNvGUj0aejhYpca5DTjtWn8moGkaf X-Proofpoint-ORIG-GUID: ReuSF8Zpt_luHAx5WfL7f4EjKRbKkOln X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.28.16 definitions=2024-06-27_14,2024-06-27_03,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 adultscore=0 spamscore=0 mlxlogscore=654 priorityscore=1501 bulkscore=0 impostorscore=0 suspectscore=0 mlxscore=0 lowpriorityscore=0 clxscore=1015 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2406140001 definitions=main-2406270134 This reverts commit 7c3ded5735141ff4d049747c9f76672a8b737c49. On PowerNV, when a nested guest tries to use a feature prohibited by HFSCR, the nested hypervisor (L1) should get a H_FAC_UNAVAILABLE trap and then L1 can emulate the feature. But with the change introduced by commit 7c3ded573514 ("KVM: PPC: Book3S HV Nested: Stop forwarding all HFUs to L1") the L1 ends up getting a H_EMUL_ASSIST because of which, the L1 ends up injecting a SIGILL when L2 (nested guest) tries to use doorbells. Signed-off-by: Gautam Menghani Reviewed-by: Nicholas Piggin --- arch/powerpc/kvm/book3s_hv.c | 31 ++----------------------------- 1 file changed, 2 insertions(+), 29 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index daaf7faf21a5..cea28ac05923 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2052,36 +2052,9 @@ static int kvmppc_handle_nested_exit(struct kvm_vcpu *vcpu) fallthrough; /* go to facility unavailable handler */ #endif - case BOOK3S_INTERRUPT_H_FAC_UNAVAIL: { - u64 cause = vcpu->arch.hfscr >> 56; - - /* - * Only pass HFU interrupts to the L1 if the facility is - * permitted but disabled by the L1's HFSCR, otherwise - * the interrupt does not make sense to the L1 so turn - * it into a HEAI. - */ - if (!(vcpu->arch.hfscr_permitted & (1UL << cause)) || - (vcpu->arch.nested_hfscr & (1UL << cause))) { - ppc_inst_t pinst; - vcpu->arch.trap = BOOK3S_INTERRUPT_H_EMUL_ASSIST; - - /* - * If the fetch failed, return to guest and - * try executing it again. - */ - r = kvmppc_get_last_inst(vcpu, INST_GENERIC, &pinst); - vcpu->arch.emul_inst = ppc_inst_val(pinst); - if (r != EMULATE_DONE) - r = RESUME_GUEST; - else - r = RESUME_HOST; - } else { - r = RESUME_HOST; - } - + case BOOK3S_INTERRUPT_H_FAC_UNAVAIL: + r = RESUME_HOST; break; - } case BOOK3S_INTERRUPT_HV_RM_HARD: vcpu->arch.trap = 0;