From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B9F8E1FCFE5 for ; Tue, 11 Feb 2025 12:36:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739277401; cv=none; b=hQ4z3jjqQ3NJ6EUZp52Pjkuq7P27rhpxXOkU55TejnRkrBFNl5CJT1MzMSQuBeYx8h973GKzqQUsjOIhDpVLdMZ98YYPUQzvfaYHPR+y4ulig5t5L0cOIzfS3R0hVHAEc+lyN6PKyqbjWm4g7U44XWnVr3yYiPkxYGAem3bHKDA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739277401; c=relaxed/simple; bh=Ttmeqgnv2ilpTlQqlY790DVU6ka7haU77u2bRHQqzc0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ywo8ptIcDRia+G6w1d/1ZJN4P6UkaxX9nxB0LeCaR1C5e+DnUXh66zCBjXujw/3uUtl8aR8vXmC7h0P16BRrW1tEjrc38EQ//taRgDiJD2O1OF0pJ1rkrrQfMvI/VSeCLuCR52SDaifwHxRlBNJXtNdXtnb9ywxOYkL/PxK9gHk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8F48D1424; Tue, 11 Feb 2025 04:37:00 -0800 (PST) Received: from J2N7QTR9R3 (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A8A6C3F6A8; Tue, 11 Feb 2025 04:36:37 -0800 (PST) Date: Tue, 11 Feb 2025 12:36:35 +0000 From: Mark Rutland To: Marc Zyngier Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Joey Gouly , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Fuad Tabba Subject: Re: [PATCH 06/18] KVM: arm64: Plug FEAT_GCS handling Message-ID: References: <20250210184150.2145093-1-maz@kernel.org> <20250210184150.2145093-7-maz@kernel.org> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250210184150.2145093-7-maz@kernel.org> On Mon, Feb 10, 2025 at 06:41:37PM +0000, Marc Zyngier wrote: > We don't seem to be handling the GCS-specific exception class. > Handle it by delivering an UNDEF to the guest, and populate the > relevant trap bits. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/kvm/handle_exit.c | 11 +++++++++++ > arch/arm64/kvm/sys_regs.c | 8 ++++++++ > 2 files changed, 19 insertions(+) > > diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c > index 4f8354bf7dc5f..624a78a99e38a 100644 > --- a/arch/arm64/kvm/handle_exit.c > +++ b/arch/arm64/kvm/handle_exit.c > @@ -294,6 +294,16 @@ static int handle_svc(struct kvm_vcpu *vcpu) > return 1; > } > > +static int kvm_handle_gcs(struct kvm_vcpu *vcpu) > +{ > + /* We don't expect GCS, so treat it with contempt */ > + if (kvm_has_feat(vcpu->kvm, ID_AA64PFR1_EL1, GCS, IMP)) > + WARN_ON_ONCE(1); Just to check / better my understanging, do we enforce that this can't be exposed to the guest somewhere? I see __kvm_read_sanitised_id_reg() masks it out, and the sys_reg_descs table has it filtered, but I'm not immediately sure whether that prevents host userspace maliciously setting this? Otherwise this looks good to me. Mark. > + > + kvm_inject_undefined(vcpu); > + return 1; > +} > + > static int handle_ls64b(struct kvm_vcpu *vcpu) > { > struct kvm *kvm = vcpu->kvm; > @@ -384,6 +394,7 @@ static exit_handle_fn arm_exit_handlers[] = { > [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, > [ESR_ELx_EC_FP_ASIMD] = kvm_handle_fpasimd, > [ESR_ELx_EC_PAC] = kvm_handle_ptrauth, > + [ESR_ELx_EC_GCS] = kvm_handle_gcs, > }; > > static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 18721c773475d..2ecd0d51a2dae 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -5056,6 +5056,14 @@ void kvm_calculate_traps(struct kvm_vcpu *vcpu) > HFGITR_EL2_nBRBIALL); > } > > + if (!kvm_has_feat(kvm, ID_AA64PFR1_EL1, GCS, IMP)) { > + kvm->arch.fgu[HFGxTR_GROUP] |= (HFGxTR_EL2_nGCS_EL0 | > + HFGxTR_EL2_nGCS_EL1); > + kvm->arch.fgu[HFGITR_GROUP] |= (HFGITR_EL2_nGCSPUSHM_EL1 | > + HFGITR_EL2_nGCSSTR_EL1 | > + HFGITR_EL2_nGCSEPP); > + } > + > set_bit(KVM_ARCH_FLAG_FGU_INITIALIZED, &kvm->arch.flags); > out: > mutex_unlock(&kvm->arch.config_lock); > -- > 2.39.2 >