From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-86.mta0.migadu.com [91.218.175.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE60D4AF69E for ; Tue, 15 Sep 2026 12:39:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.86 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789475966; cv=none; b=k0HAsslnCcq5WffGqBJogSRlg83wANmlmpPkneoBFDVmLFVCaV5czd0qC5oGB1Y45kya8rSElvC84kFkcJ5+irTmrBBjSykcEBfInI2qjl1ZckyKBGucsOcBg4Tm2W6D7SVRnHlK9STeevuyRW2vDcVSpxy3Tn2HYWxOGHbmKVg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789475966; c=relaxed/simple; bh=rjKovHQD0Gp4G9kJIm0gEuJ0ORCBHOkqoPL4YmXSz3E=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=OTnmpXRMI9mebYHx4Bts2KeRs5vdpYSK3xFz1oSsSmqvaltt8OBXuSTSs/zBtzCP1PzkY6j/JGAgTWo/FNgvH7m4s7AK3+C63kIxkUKesTL9ccMvCgy6z5MBlLiexvbi3YOeSbV59YVCH2lMkJR7pwi0dnZBA87eSB7+yYg5cGA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=kbeicyrG; arc=none smtp.client-ip=91.218.175.86 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="kbeicyrG" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=rjKovHQD0Gp4G9kJIm0gEuJ0ORCBHOkqoPL4YmXSz3E=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1789475962; v=1; x=1790080762; b=kbeicyrGZUNKrROuGHQIdQYDegthU180uE8j/HcfOoz4MyDSyV/4lz+PuhLH5Ealxtuy72m2 b5UVbGnlrNs+UmXxgWXlXz01Qf3Joq9niMvmMDQqlIPPVfKhGbUqdyAN7HnVVTT+6PH49JNEX1P MdOJ935UjsuPFt6H4Q0hRzfw= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id cd327d75635f7551; Tue, 15 Sep 2026 12:39:22 +0000 X-Mizu-Trace-ID: cd327d75635f7551 X-Migadu-Flow: FLOW_OUT From: Fuad Tabba To: maz@kernel.org, oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: catalin.marinas@arm.com, will@kernel.org, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, mark.rutland@arm.com, vdonnefort@google.com, qperret@google.com, Sascha.Bischoff@arm.com, steven.price@arm.com, tabba@google.com Subject: [PATCH 5/7] KVM: arm64: Pin the host vCPU before adjusting its PC under pKVM Date: Tue, 15 Sep 2026 13:38:44 +0100 Message-Id: <20260915123846.2317931-6-fuad.tabba@linux.dev> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260915123846.2317931-1-fuad.tabba@linux.dev> References: <20260915123846.2317931-1-fuad.tabba@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Under pKVM, a page the host shares with EL2 is mapped at EL2 only while it's pinned, and the host vCPU is pinned at its first KVM_RUN. KVM_SET_VCPU_EVENTS with ext_dabt_pending reaches __kvm_adjust_pc() at EL2 before that, and dereferencing the unmapped host vCPU panics the hypervisor. Any process holding /dev/kvm on a pKVM host can trigger it. Pin the host vCPU around the adjustment when no hyp vCPU is loaded for it. A loaded hyp vCPU implies it's pinned. A pin fails only for memory the host isn't sharing, and the request is then dropped like any other bad host pointer. Fixes: efa1368ba9f4b ("KVM: arm64: Commit exceptions from KVM_SET_VCPU_EVENTS immediately") Reviewed-by: Vincent Donnefort Reviewed-by: Joey Gouly Cc: stable@vger.kernel.org Signed-off-by: Fuad Tabba --- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index b2657a3c65b40..a138b42e7cea3 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -542,8 +542,27 @@ static void handle___pkvm_host_mkyoung_guest(struct kvm_cpu_context *host_ctxt) static void handle___kvm_adjust_pc(struct kvm_cpu_context *host_ctxt) { DECLARE_REG(struct kvm_vcpu *, vcpu, host_ctxt, 1); + struct pkvm_hyp_vcpu *hyp_vcpu; + struct kvm_vcpu *host_vcpu; - __kvm_adjust_pc(kern_hyp_va(vcpu)); + host_vcpu = __get_host_hyp_vcpus(vcpu, &hyp_vcpu); + if (host_vcpu) { + __kvm_adjust_pc(host_vcpu); + return; + } + + /* + * With no hyp vCPU loaded for it, the host vCPU may be unpinned, + * and so unmapped at EL2: its first run pins it. A pin fails only + * for memory the host isn't sharing, a bad pointer, so the request + * is dropped. + */ + host_vcpu = kern_hyp_va(vcpu); + if (hyp_pin_shared_mem(host_vcpu, host_vcpu + 1)) + return; + + __kvm_adjust_pc(host_vcpu); + hyp_unpin_shared_mem(host_vcpu, host_vcpu + 1); } static void handle___kvm_flush_vm_context(struct kvm_cpu_context *host_ctxt) -- 2.39.5