From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-68.mta0.migadu.com [91.218.175.68]) (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 39FB21FBEA8 for ; Mon, 7 Sep 2026 07:01:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.68 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788764494; cv=none; b=Y3L/wAR0tBvSjD1v6Fp3HviY9DwpRrKKBV3Iu8ZRiFZrbaRGY99SMuZ9sBmLp+sM3JaW5QNJACcZdoUr07iTu5UE9yWV9MROO5VJgkTGX1KKeYU9e15SslB5VzAnE8IIr9+Aiw6mb9dVOPTxoabBqs8RzdswD3C9YdTp7GtQAxU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788764494; c=relaxed/simple; bh=UrkAa/Ibk4oC0D29/DNAsgafr0M8SDNie/XH9u/vDGg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=aBuJs3l/LANw7+nixBEkUKVkPo2sYfDRkvFg1xiPzYmvegl2ohfviXSs/+ELKife/Ow/3s4CAMq0y+68R0AKnMTUOnX0FvqFRYOxm6XoX0MeopG6OTkmd5HDFhUTp6/9ChB7rv7K/95xXE2z1i439MvmXlylPrjdOuvdn3ezon0= 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=jsGVX4Lj; arc=none smtp.client-ip=91.218.175.68 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="jsGVX4Lj" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=UrkAa/Ibk4oC0D29/DNAsgafr0M8SDNie/XH9u/vDGg=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788764486; v=1; x=1789369286; b=jsGVX4LjDrB/xxGxz1yid9sTviRdlwEXxqkVYIzswG3Rc0ZLGOjfGqmbwK/fczQCJD9jOcQQ TFFGWcd32hGRaDs/tCcOMvlIqFhH93TO7wBy+2x6bQg/UDDuB8fW2WhTTzkQCywKBSXIapB1rf9 k7cztB5E11JqVQZzU3d7gIng= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 64311d740072dc6d; Mon, 07 Sep 2026 07:01:26 +0000 X-Mizu-Trace-ID: 64311d740072dc6d 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 11/17] KVM: arm64: Inject an UNDEF at EL2 for unhandled protected guest exits Date: Mon, 7 Sep 2026 07:59:56 +0100 Message-Id: <20260907070002.3333525-12-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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Make pvm_exit_handlers[] an allow-list: a protected guest's exit class is handled at EL2, forwarded where the host emulates it, or results in an UNDEF at EL2. Any other class, once forwarded, would re-execute forever. The host resolves such an exit by injecting an exception or incrementing the PC. The marshalling that follows allows neither: a protected vCPU takes only the UNDEF on a SYS64 trap and the external abort on a forwarded IABT or DABT that EL2 builds for it. WFxT takes the UNDEF, as it isn't advertised to protected guests. FP/SIMD keeps the lazy switch, and the watchpoint entry is dropped: a protected vCPU runs with TDE clear. Signed-off-by: Fuad Tabba --- arch/arm64/kvm/hyp/nvhe/switch.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c index 7318e3e6a5f36..afddcf14f366e 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -203,15 +203,36 @@ static const exit_handler_fn hyp_exit_handlers[] = { [ESR_ELx_EC_MOPS] = kvm_hyp_handle_mops, }; +/* WFI/WFE exit to the host, which emulates them. WFxT is not offered. */ +static bool kvm_handle_pvm_wfx(struct kvm_vcpu *vcpu, u64 *exit_code) +{ + if (kvm_vcpu_get_esr(vcpu) & ESR_ELx_WFx_ISS_WFxT) + return kvm_handle_pvm_restricted(vcpu, exit_code); + + return false; +} + +/* Lazy FP/SIMD switch, or the UNDEF the host would otherwise be asked for. */ +static bool kvm_handle_pvm_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code) +{ + if (kvm_hyp_handle_fpsimd(vcpu, exit_code)) + return true; + + return kvm_handle_pvm_restricted(vcpu, exit_code); +} + +/* + * A class not listed takes an UNDEF at EL2: the host has no way to + * inject one into a protected vCPU. + */ static const exit_handler_fn pvm_exit_handlers[] = { - [0 ... ESR_ELx_EC_MAX] = NULL, + [0 ... ESR_ELx_EC_MAX] = kvm_handle_pvm_restricted, + [ESR_ELx_EC_WFx] = kvm_handle_pvm_wfx, [ESR_ELx_EC_HVC64] = kvm_handle_pvm_hvc64, [ESR_ELx_EC_SYS64] = kvm_handle_pvm_sys64, - [ESR_ELx_EC_SVE] = kvm_handle_pvm_restricted, - [ESR_ELx_EC_FP_ASIMD] = kvm_hyp_handle_fpsimd, + [ESR_ELx_EC_FP_ASIMD] = kvm_handle_pvm_fpsimd, [ESR_ELx_EC_IABT_LOW] = kvm_hyp_handle_iabt_low, [ESR_ELx_EC_DABT_LOW] = kvm_hyp_handle_dabt_low, - [ESR_ELx_EC_WATCHPT_LOW] = kvm_hyp_handle_watchpt_low, [ESR_ELx_EC_MOPS] = kvm_hyp_handle_mops, }; -- 2.39.5