From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A04D1C79F89 for ; Mon, 7 Sep 2026 07:02:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=XUMIPY/FkInwKttBwikvMs05k8i52NwUeocA8MsUCKE=; b=caDsdEPaCv0x7hLq/3cK987sa6 027XHhPgglAz5LzOeL8BGBawIUzKQRUpk2vCJddzoibfBamm6hHiNx46FMJrMcRHH4aHBDNOg2H5a KnxZx00NAiwk9GjSi9UixMFQlpwRYhNTJUDWO+uLvWINcri6MOGpe1VGx6Ps7idNzgKFtlh2lq9+Z yyNSUCsIfxqUh5S4KB7t4kzA/snh1TbGkD0ru53PXxu0yu6PNXA8REM5rdkaXixmy2OCsCuLRq0hM /P2CMyq6Cj7Qzw7Y7OsdEHBajeEtRz3sFmisDUi1zzZjWNll21mPF/nIcCDJ0eczpybcv+nNFsXnc Kr9FBzNQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3TMo-000000066qW-02n5; Mon, 07 Sep 2026 07:02:10 +0000 Received: from out-27.mta0.migadu.com ([2001:41d0:1004:224b::1b] helo=mta0.migadu.com) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3TMg-000000066lF-3P3v for linux-arm-kernel@lists.infradead.org; Mon, 07 Sep 2026 07:02:07 +0000 X-Envelope-To: linux-arm-kernel@lists.infradead.org DKIM-Signature: a=rsa-sha256; bh=W0TO4ClCsD7vi8bGBZFX+iW0Jm2NqILqAoXbCQSbJ40=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788764520; v=1; x=1789369320; b=jUZZelfKJsuWl7lCeskWVPrEPeH5WsZXq08MW253xSw0+EdHXgy/7LWUiiekAlmUchbkXAL0 gffHgWEwZGVdvrEcSZ6EmpcvrOoJNjouEBnXRek14L8XX7mHMMJXm03OphF3BLMz+jne4j0osb8 mJsA2bCnwHPdFRXah5dLj+Gk= X-Envelope-To: linux-arm-kernel@lists.infradead.org Received: by smtp.migadu.com with ESMTPS id 4efff04413af64b4; Mon, 07 Sep 2026 07:02:00 +0000 X-Mizu-Trace-ID: 4efff04413af64b4 X-Migadu-Flow: FLOW_OUT From: Fuad Tabba To: Marc Zyngier , Oliver Upton , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Catalin Marinas , Will Deacon , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Vincent Donnefort , Quentin Perret , Fuad Tabba Subject: [PATCH v2 15/17] KVM: arm64: Reject host power-on of a vCPU that EL2 holds powered off Date: Mon, 7 Sep 2026 08:00:00 +0100 Message-Id: <20260907070002.3333525-16-fuad.tabba@linux.dev> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260907070002.3333525-1-fuad.tabba@linux.dev> References: <20260907070002.3333525-1-fuad.tabba@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260907_000205_406474_BFF58558 X-CRM114-Status: GOOD ( 15.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org A protected vCPU's power state belongs to EL2, which changes it only on the guest's own PSCI calls. KVM_SET_MP_STATE(RUNNABLE) on a vCPU EL2 holds powered off changes the host's copy alone, and the guest's next CPU_ON of that vCPU then fails: mp_state is no longer STOPPED, so the host returns ALREADY_ON, which EL2 turns into INTERNAL_FAILURE. SUSPENDED has the same effect. Track at the host whether EL2 holds a protected vCPU powered off and return -EPERM for both writes in that state. STOPPED stays permitted, so a VMM can pause a vCPU, and RUNNABLE on a vCPU EL2 has powered on, so it can resume one. Signed-off-by: Fuad Tabba --- arch/arm64/include/asm/kvm_host.h | 2 ++ arch/arm64/kvm/arm.c | 19 +++++++++++++++++++ arch/arm64/kvm/pkvm.c | 21 +++++++++++++++++---- arch/arm64/kvm/psci.c | 3 +++ 4 files changed, 41 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 78a4d387f9fd4..39788c4331260 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -922,6 +922,8 @@ struct kvm_vcpu_arch { /* vcpu power state */ struct kvm_mp_state mp_state; spinlock_t mp_state_lock; + /* EL2 holds the protected vCPU powered off. Under mp_state_lock. */ + bool pkvm_powered_off; /* Cache some mmu pages needed inside spinlock regions */ struct kvm_mmu_memory_cache mmu_page_cache; diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 37a260b139795..6bed18837f2e1 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -777,9 +777,12 @@ static void __kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu) kvm_vcpu_kick(vcpu); } +/* The guest's own CPU_OFF: EL2 has already powered the vCPU off. */ void kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu) { spin_lock(&vcpu->arch.mp_state_lock); + if (vcpu_is_protected(vcpu)) + vcpu->arch.pkvm_powered_off = true; __kvm_arm_vcpu_power_off(vcpu); spin_unlock(&vcpu->arch.mp_state_lock); } @@ -801,6 +804,12 @@ static bool kvm_arm_vcpu_suspended(struct kvm_vcpu *vcpu) return READ_ONCE(vcpu->arch.mp_state.mp_state) == KVM_MP_STATE_SUSPENDED; } +/* Only the guest's CPU_ON may start a vCPU EL2 holds powered off. */ +static bool kvm_pkvm_vcpu_is_powered_off(struct kvm_vcpu *vcpu) +{ + return vcpu_is_protected(vcpu) && vcpu->arch.pkvm_powered_off; +} + int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu, struct kvm_mp_state *mp_state) { @@ -818,12 +827,22 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, switch (mp_state->mp_state) { case KVM_MP_STATE_RUNNABLE: + if (kvm_pkvm_vcpu_is_powered_off(vcpu)) { + ret = -EPERM; + break; + } + WRITE_ONCE(vcpu->arch.mp_state, *mp_state); break; case KVM_MP_STATE_STOPPED: __kvm_arm_vcpu_power_off(vcpu); break; case KVM_MP_STATE_SUSPENDED: + if (kvm_pkvm_vcpu_is_powered_off(vcpu)) { + ret = -EPERM; + break; + } + kvm_arm_vcpu_suspend(vcpu); break; default: diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c index 8e4c6e4bec123..388c89f637b85 100644 --- a/arch/arm64/kvm/pkvm.c +++ b/arch/arm64/kvm/pkvm.c @@ -118,12 +118,25 @@ static int __pkvm_create_hyp_vcpu(struct kvm_vcpu *vcpu) return -ENOMEM; ret = kvm_call_hyp_nvhe(__pkvm_init_vcpu, handle, vcpu, hyp_vcpu); - if (!ret) - vcpu_set_flag(vcpu, VCPU_PKVM_FINALIZED); - else + if (ret) { free_pages_exact(hyp_vcpu, hyp_vcpu_sz); + return ret; + } - return ret; + /* + * Mirror EL2's seeding of power_state from mp_state. The hyp vCPU is + * published, so take mp_state_lock against kvm_psci_vcpu_on(). + */ + if (vcpu_is_protected(vcpu)) { + spin_lock(&vcpu->arch.mp_state_lock); + if (kvm_arm_vcpu_stopped(vcpu)) + vcpu->arch.pkvm_powered_off = true; + spin_unlock(&vcpu->arch.mp_state_lock); + } + + vcpu_set_flag(vcpu, VCPU_PKVM_FINALIZED); + + return 0; } /* diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c index e3db84400d1f8..208289a08099f 100644 --- a/arch/arm64/kvm/psci.c +++ b/arch/arm64/kvm/psci.c @@ -94,6 +94,9 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) */ smp_wmb(); + /* EL2 has committed the protected vCPU to ON_PENDING to get here. */ + vcpu->arch.pkvm_powered_off = false; + WRITE_ONCE(vcpu->arch.mp_state.mp_state, KVM_MP_STATE_RUNNABLE); kvm_vcpu_wake_up(vcpu); -- 2.39.5