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bh=ua8GfkfDrHDUR8px+Sy19+vmLzFSWzTq6VAHh+SakiE=; b=eEoqjwvVLdUmHzGf1BYkqFAqFI76KRe1hdWm/bq5J0fJab6hyOR5P/bXJHuwLcdGqY e9vXHgYN5QzFp0EUFG62uvHUI/2aZjCVDpMfzPdIVzTGK6Y9F+wHT3Tn0YYyASN7u40n c7/U+jG0q78p4Aqa2KcqI621RKp1QnWc6IAL29vn+4q3etb1j9XkU8zIyrAfEeDE9+4I VMS1Xd7VwlHpJm/n0cBNyhPuffNIBkGqhIw7AUmBKJCmBRay0T/gKInSt925/BfpLhZ3 5YkxF5vLE2qMZYOFNpKWp0cBXfAB6QNgWNodUkSAqwchBdUoDDZtxwwW4AR9QT6J+Gf1 whSg== X-Forwarded-Encrypted: i=1; AKwUvBxRYeD/mJZw3VoKn/BbhGvl278+szGPiAQFBRQgX+RDQSW4xFPvVH1RF6AjZJT3rJbYCR2G2t7XCqcS7cw=@lists.ozlabs.org X-Gm-Message-State: AFq9FYLNCJ+77ugiFJjKY7g2u+jx1xMRrzTi7fdetBElpX+9vBAQiqP0 rYJPeKQkuUt2F7FtPOWjkdkrC82+7C+1hfSAsfuBnVkFzkHFzp+2b+EAJDm/9eIKbtfkeMpvU08 /aZjs3Q== X-Received: from pjbov14.prod.google.com ([2002:a17:90b:258e:b0:3a8:d9d:78ef]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:224f:b0:3a0:b312:1fbe with SMTP id 98e67ed59e1d1-3ae580a7ac7mr2187674a91.23.1793214184152; Wed, 28 Oct 2026 12:03:04 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 28 Oct 2026 12:02:54 -0700 In-Reply-To: <20261028190259.1819571-1-seanjc@google.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , Precedence: list X-Archived-By: Mime-Version: 1.0 References: <20261028190259.1819571-1-seanjc@google.com> X-Mailer: git-send-email 2.56.0.313.g2479322e68-goog Message-ID: <20261028190259.1819571-3-seanjc@google.com> Subject: [PATCH 2/7] KVM: Add a @force param to __kvm_vcpu_kick() for PPC backwards compatibility From: Sean Christopherson To: Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Madhavan Srinivasan , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Paolo Bonzini Cc: Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Nicholas Piggin , Atish Patra , Alexandre Ghiti , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Stefan Teodorescu Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Plumb in a @force param to __kvm_vcpu_kick() to force an IPI without checking kvm_arch_vcpu_should_kick(). The param will be used to drop kvm_arch_vcpu_should_kick() in favor of kvm_request_needs_ipi() without regressing PPC, which for unknown reasons unconditionally blasts an IPI in a variety of kvm_vcpu_kick() flows. No functional change intended (nothing yet passes in @force=true). Signed-off-by: Sean Christopherson --- include/linux/kvm_host.h | 6 +++--- virt/kvm/kvm_main.c | 10 +++++++--- 2 files changed, 10 insertions(+), 6 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index e7fc94e2910a..3b9844c3906d 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1570,11 +1570,11 @@ void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu); bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu); #ifndef CONFIG_S390 -void __kvm_vcpu_kick(struct kvm_vcpu *vcpu, bool wait); +void __kvm_vcpu_kick(struct kvm_vcpu *vcpu, bool wait, bool force); static inline void kvm_vcpu_kick(struct kvm_vcpu *vcpu) { - __kvm_vcpu_kick(vcpu, false); + __kvm_vcpu_kick(vcpu, false, false); } #endif @@ -2315,7 +2315,7 @@ static __always_inline void kvm_make_request(int req, struct kvm_vcpu *vcpu) static inline void kvm_make_request_and_kick(int req, struct kvm_vcpu *vcpu) { kvm_make_request(req, vcpu); - __kvm_vcpu_kick(vcpu, req & KVM_REQUEST_WAIT); + __kvm_vcpu_kick(vcpu, req & KVM_REQUEST_WAIT, false); } #endif diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index cf4cb586f140..67addb9e48a7 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3908,7 +3908,7 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_vcpu_wake_up); /* * Kick a sleeping VCPU, or a guest VCPU in guest mode, into host kernel mode. */ -void __kvm_vcpu_kick(struct kvm_vcpu *vcpu, bool wait) +void __kvm_vcpu_kick(struct kvm_vcpu *vcpu, bool wait, bool force) { int me, cpu; @@ -3933,9 +3933,13 @@ void __kvm_vcpu_kick(struct kvm_vcpu *vcpu, bool wait) * after kvm_arch_vcpu_should_kick(), which could result in sending an * IPI to the previous pCPU. But, that's ok because the purpose of the * IPI is to force the vCPU to leave IN_GUEST_MODE, and migrating the - * vCPU also requires it to leave IN_GUEST_MODE. + * vCPU also requires it to leave IN_GUEST_MODE + * + * Note #2, do NOT check if an IPI is needed if @force is true, as the + * check also modifies vcpu->mode and KVM PPC needs to avoid that side + * effect for unknown historical reasons. */ - if (kvm_arch_vcpu_should_kick(vcpu)) { + if (force || kvm_arch_vcpu_should_kick(vcpu)) { cpu = READ_ONCE(vcpu->cpu); if (cpu != me && (unsigned int)cpu < nr_cpu_ids && cpu_online(cpu)) { /* -- 2.56.0.313.g2479322e68-goog