From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793829216; b=yHFQv7z69CJuo92jJeWw8Y/9rUMk0crA7+a6EkbRx6ibmUCejrD2WoS/NFgWiL1dDGxi y/aUKEJ+xvjAI3yEG9RxnjIHTu6NpvZ+Vsktc2nQKziuroxB14WKtvLgevJtXiJlCc1TS a6zk8JKx73I70kgypMRo4ZnzwI1atKgO0OlbOxYJjvfRnBm/doUHNeMrfPJuu9cvhhwb5 Ch7GgVmckV/mVJb7skBjzz9URkDMpd37WMFRr0ibM/7E2/sas4z4Y9VjlzU91MyGAPVWG vjOydU+/zjl/XtMN0GpajF28jRxVw+od6kGdJf1IU4pd59uYOLYf08XvwHgV3Hq0Qbw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793829216; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=dlFgcRgRBqBeHByj51RbtdySKPUtNoJ40vu3mosPVy8=; b=0OMVTfjYAN4mY1SMTqSYMs57Y3ho8X7FTBwhh5WaQVTvKy5GI7Lv/xrQHpTiBQIPG+81 J7TQZXUK4e5QK7SBimeKA14I3d8XltolipaG8PmXZppyWZESvmD+jpK4REsQTvLbba106 0S7gDaG2PoLvG842Nwf8MIAHMeMQTTLH4fLZ08viqJ2VkLa5pGfcKYjg6MfnlA6ZKNTm2 kDn0ne4n26Ii/PB1HWF5kbv8bl72IsvpCdjsb/0Lc8rdBM8iT14WnW/x5jv+0kq1R/QJ+ fuTujvtwmtxhuFldvZjfAEuBLJK8ToI/VXpnLn7DlRvrg6gnzaQaxe/U2oB1g2V9yHw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=IFr64U8N; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A40736070A88; Wed, 4 Nov 2026 21:53:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=IFr64U8N Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26AE11F00A18; Wed, 4 Nov 2026 21:53:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793829215; bh=dlFgcRgRBqBeHByj51RbtdySKPUtNoJ40vu3mosPVy8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IFr64U8NASNmNEvky62mfwiERLXVcQ10D5dIbxp4fMEbIzk/o+Vz/n3oODM+/61xr Knu7yOlNVXqNLB4zbhVfSdp8ceKmpEcTNtc9c7CQ3nulUAs2x++3CVco1OCbx42YfG bDMA4RmwAeXAx+lp8va0uzmHa/KZvVAvfJPxlfs4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Amit Machhiwal , "Ritesh Harjani (IBM)" , Madhavan Srinivasan Subject: [PATCH 7.3 481/547] KVM: PPC: Book3S HV: Add preempt_disable() around virtual-mode HPTE bit-lock users Date: Wed, 4 Nov 2026 16:11:05 -0500 Message-ID: <20261104211052.041001178@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211038.406938024@linuxfoundation.org> References: <20261104211038.406938024@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Amit Machhiwal commit abbbe5ff83e7c9ed3a4d61b73011f1df7bf87907 upstream. kvmppc_hv_find_lock_hpte() requires virtual-mode callers to run with preemption disabled, because it can return with HPTE_V_HVLOCK still held until the caller later unlocks the HPTE. Existing virtual-mode callers in book3s_64_mmu_hv.c already follow that rule. Two virtual-mode call paths do not: 1. kvmppc_handle_exit_hv() calls kvmppc_hpte_hv_fault() for hash-mode data-side and instruction-side faults after guest exit, with preemption already enabled. kvmppc_hpte_hv_fault() calls kvmppc_hv_find_lock_hpte() directly. 2. kvmppc_pseries_do_hcall() executes virtual-mode handlers for HPT hcalls via kvmppc_pseries_do_hpt_hcall() with preemption enabled. The handlers for H_ENTER, H_REMOVE, H_READ, H_CLEAR_MOD, H_CLEAR_REF, H_PROTECT, and H_BULK_REMOVE spin on try_lock_hpte() or lock_rmap(), and H_ENTER also reaches kvmppc_do_h_enter(), which uses arch_spin_lock() on kvm->mmu_lock. That raw lock choice is intentional because kvmppc_do_h_enter() is also used by real-mode callers, so the correct fix is to establish the proper preemption context at the virtual-mode caller boundary. If a vCPU thread is preempted while holding HPTE_V_HVLOCK, any other thread on the same CPU trying to acquire the same bit-lock can spin indefinitely. The same applies to lock_rmap() users and to the H_ENTER path while holding the raw mmu_lock. Fix this by adding preempt_disable()/preempt_enable() pairs around the two kvmppc_hpte_hv_fault() call sites in kvmppc_handle_exit_hv(), and around the kvmppc_pseries_do_hpt_hcall() invocation in kvmppc_pseries_do_hcall(). Targeting only the HPT hcall helper avoids wrapping non-HPT hcalls (such as H_RTAS, H_CONFER, H_REGISTER_VPA) that perform page faults, blocking memory allocations, or context switches. Fixes: 6165d5dd99db ("KVM: PPC: Book3S HV: add virtual mode handlers for HPT hcalls and page faults") Cc: stable@vger.kernel.org # v5.14+ Signed-off-by: Amit Machhiwal Reviewed-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260928122837.8782-3-amachhiw@linux.ibm.com Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kvm/book3s_hv.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1212,9 +1212,11 @@ int kvmppc_pseries_do_hcall(struct kvm_v case H_CLEAR_REF: case H_PROTECT: case H_BULK_REMOVE: + preempt_disable(); idx = srcu_read_lock(&kvm->srcu); ret = kvmppc_pseries_do_hpt_hcall(vcpu, req); srcu_read_unlock(&kvm->srcu, idx); + preempt_enable(); if (ret == H_TOO_HARD) return RESUME_HOST; break; @@ -1834,8 +1836,10 @@ static int kvmppc_handle_exit_hv(struct else vsid = vcpu->arch.fault_gpa; + preempt_disable(); err = kvmppc_hpte_hv_fault(vcpu, vcpu->arch.fault_dar, vsid, vcpu->arch.fault_dsisr, true); + preempt_enable(); if (err == 0) { r = RESUME_GUEST; } else if (err == -1 || err == -2) { @@ -1881,8 +1885,10 @@ static int kvmppc_handle_exit_hv(struct else vsid = vcpu->arch.fault_gpa; + preempt_disable(); err = kvmppc_hpte_hv_fault(vcpu, vcpu->arch.fault_dar, vsid, vcpu->arch.fault_dsisr, false); + preempt_enable(); if (err == 0) { r = RESUME_GUEST; } else if (err == -1) {