From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8C8E62EDD63; Thu, 20 Nov 2025 14:51:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763650307; cv=none; b=g7VFGRPlUgf0ID0NRa1iPkwD6OZeuzpj0vkaXeyzxPN+dU7/uWPsVNsiHHlXy8IXOfoT9RkWcAUVJQ6A7AZRaw1mpQMIzCwbjDwZFRZ79Icmrq+BHEH/zAWVA/Fj0bVRpT2JAR09K1EXmn1etx11RDM++kgnfjcI9cvjEYc8vtw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763650307; c=relaxed/simple; bh=ouZCDzXe0QkWeDXoCSvcmRScnrUHUe4hSuaj1XU5F+U=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=C55zcRuk/gVUaIed6bYLPKUCrhu/+U50fObC2vNhterrI6OIDdKjq5CqaK/M/hPYewqB1d+3fvpzfEJIx9M2J5OMUcSxcV5SsBt+docmBHUhSWYWUbxXvRN7nKkxFwRTWx/8GKyvWShy3JSxVWFXQxGMHNduDIebnlD1BoevvDY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vBz3rTp4; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="vBz3rTp4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40641C4CEF1; Thu, 20 Nov 2025 14:51:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763650307; bh=ouZCDzXe0QkWeDXoCSvcmRScnrUHUe4hSuaj1XU5F+U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=vBz3rTp4TiwEolvj0ix9cNHs80qhWuY1pphniGXdk7OUuT0hg+2TsimukVjy6ql3D QJMdBcGQzA33jyQewLfOsZG5ASrvHM615jFGVo/qqFuk2jirrZv6K5lRxkYIB00R5A eqE+DxBzRO+TN11Fil+w0ImoCFxw0kPOcQbBgR3HqQbfE1tye6avqD91wx/kehw33N E0/p5nwWN6PveN3aNWy9t8BcA4aEM0v7Hoa9aqyOEvX7zgOHqPgHjf13B3SJt1gLPe NYovawPF1wppFuXDSiEePvlozSLB3ASUUw0GrQ9JE+ica4luV6/5mEsP5TzdJNKOh1 VKd3osOrKYubw== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vM60f-00000006v9Y-0d3d; Thu, 20 Nov 2025 14:51:45 +0000 Date: Thu, 20 Nov 2025 14:51:44 +0000 Message-ID: <865xb4sqnz.wl-maz@kernel.org> From: Marc Zyngier To: Joey Gouly Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Suzuki K Poulose , Oliver Upton , Zenghui Yu Subject: Re: [PATCH 2/5] KVM: arm64: Force trap of GMID_EL1 when the guest doesn't have MTE In-Reply-To: <20251120143419.GA2325986@e124191.cambridge.arm.com> References: <20251120133202.2037803-1-maz@kernel.org> <20251120133202.2037803-3-maz@kernel.org> <20251120143419.GA2325986@e124191.cambridge.arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: joey.gouly@arm.com, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, suzuki.poulose@arm.com, oupton@kernel.org, yuzenghui@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Thu, 20 Nov 2025 14:34:19 +0000, Joey Gouly wrote: > > On Thu, Nov 20, 2025 at 01:31:59PM +0000, Marc Zyngier wrote: > > If our host has MTE, but the guest doesn't, make sure we set HCR_EL2.TID5 > > to force GMID_EL1 being trapped. > > > > Signed-off-by: Marc Zyngier > > --- > > arch/arm64/kvm/sys_regs.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > > index 84e6f04220589..40f32b017f107 100644 > > --- a/arch/arm64/kvm/sys_regs.c > > +++ b/arch/arm64/kvm/sys_regs.c > > @@ -5558,6 +5558,8 @@ static void vcpu_set_hcr(struct kvm_vcpu *vcpu) > > > > if (kvm_has_mte(vcpu->kvm)) > > vcpu->arch.hcr_el2 |= HCR_ATA; > > + else if (id_aa64pfr1_mte(read_sanitised_ftr_reg(SYS_ID_AA64PFR1_EL1))) > > + vcpu->arch.hcr_el2 |= HCR_TID5; > > This is because we want to enable the trapping regardless of CONFIG_ARM64_MTE > (so we can't use system_supports_mte()). Indeed. In general, we cannot rely on the kernel's own configuration, since the guest sees most of the actual HW. > > Reviewed-by: Joey Gouly Thanks! M. -- Without deviation from the norm, progress is not possible.