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 10B033C342C for ; Mon, 23 Mar 2026 16:47:33 +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=1774284454; cv=none; b=G0VWbRE+dEp0sA30etVlfgVaHzmPjs6RLJnL3g65n6B4ekJdQq6XW2HjhGXZ9d8O1aCwZCLYeDlTl014JGC4IiRt82CLDHd5HKSlbYURtvIa+I9abf1QffBwBdjQDL76pRib8er+hCf42FXSS6fvIgf0+CCHV0fqaoRDMm39oEE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774284454; c=relaxed/simple; bh=Dfwg60/cnQSCYcZJZuzsEBq6e/n+anP87wVWI8/mOoM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OTPBs/7fdzX5vWDmn1VqtQe4AylElCSE26x4cbq/CTU0kvcl+umLKuM7abgc+hyhiPYY2GWkGibpwPm/9yM8Wwr57yoiiwbIvbjs/imkiYisUH9Y2uLoiygNg5uzbGcJHNtT7jXPE2MEuyz1saiovBxFvd/jB92aqpsm6mjAI9s= 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 AA4251516; Mon, 23 Mar 2026 09:47:26 -0700 (PDT) Received: from e142021.fritz.box (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 10EB83F73B; Mon, 23 Mar 2026 09:47:30 -0700 (PDT) From: Andre Przywara To: Will Deacon , Julien Thierry Cc: maz@kernel.org, Sascha Bischoff , kvm@vger.kernel.org, kvmarm@lists.linux.dev, Alexandru Elisei Subject: [PATCH kvmtool v7 4/6] arm64: Add FEAT_E2H0 support Date: Mon, 23 Mar 2026 17:47:15 +0100 Message-ID: <20260323164717.2571585-5-andre.przywara@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260323164717.2571585-1-andre.przywara@arm.com> References: <20260323164717.2571585-1-andre.przywara@arm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Marc Zyngier The --nested option allows a guest to boot at EL2 without FEAT_E2H0 (i.e. mandating VHE support). While this is great for "modern" operating systems and hypervisors, a few legacy guests are stuck in a distant past. To support those, add the --e2h0 command line option, that exposes FEAT_E2H0 to the guest, at the expense of a number of other features, such as FEAT_NV2. This is conditioned on the host itself supporting FEAT_E2H0. Signed-off-by: Marc Zyngier Signed-off-by: Andre Przywara Reviewed-by: Sascha Bischoff --- arm64/include/kvm/kvm-config-arch.h | 5 ++++- arm64/kvm-cpu.c | 5 +++++ arm64/kvm.c | 3 +++ 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/arm64/include/kvm/kvm-config-arch.h b/arm64/include/kvm/kvm-config-arch.h index 44c43367..73bf4211 100644 --- a/arm64/include/kvm/kvm-config-arch.h +++ b/arm64/include/kvm/kvm-config-arch.h @@ -11,6 +11,7 @@ struct kvm_config_arch { bool has_pmuv3; bool mte_disabled; bool nested_virt; + bool e2h0; u64 kaslr_seed; enum irqchip_type irqchip; u64 fw_addr; @@ -63,6 +64,8 @@ int sve_vl_parser(const struct option *opt, const char *arg, int unset); OPT_U64('\0', "counter-offset", &(cfg)->counter_offset, \ "Specify the counter offset, defaulting to 0"), \ OPT_BOOLEAN('\0', "nested", &(cfg)->nested_virt, \ - "Start VCPUs in EL2 (for nested virt)"), + "Start VCPUs in EL2 (for nested virt)"), \ + OPT_BOOLEAN('\0', "e2h0", &(cfg)->e2h0, \ + "Create guest without VHE support"), #endif /* ARM_COMMON__KVM_CONFIG_ARCH_H */ diff --git a/arm64/kvm-cpu.c b/arm64/kvm-cpu.c index 42dc11da..5e4f3a7d 100644 --- a/arm64/kvm-cpu.c +++ b/arm64/kvm-cpu.c @@ -76,6 +76,11 @@ static void kvm_cpu__select_features(struct kvm *kvm, struct kvm_vcpu_init *init if (!kvm__supports_extension(kvm, KVM_CAP_ARM_EL2)) die("EL2 (nested virt) is not supported"); init->features[0] |= 1UL << KVM_ARM_VCPU_HAS_EL2; + if (kvm->cfg.arch.e2h0) { + if (!kvm__supports_extension(kvm, KVM_CAP_ARM_EL2_E2H0)) + die("FEAT_E2H0 is not supported"); + init->features[0] |= 1UL << KVM_ARM_VCPU_HAS_EL2_E2H0; + } } } diff --git a/arm64/kvm.c b/arm64/kvm.c index 6e971dd7..4ce24933 100644 --- a/arm64/kvm.c +++ b/arm64/kvm.c @@ -440,6 +440,9 @@ void kvm__arch_validate_cfg(struct kvm *kvm) kvm->cfg.ram_addr + kvm->cfg.ram_size > SZ_4G) { die("RAM extends above 4GB"); } + + if (kvm->cfg.arch.e2h0 && !kvm->cfg.arch.nested_virt) + pr_warning("--e2h0 requires --nested, ignoring"); } u64 kvm__arch_default_ram_address(void) -- 2.43.0