[PATCH v2 23/24] KVM: arm64: Don't map host sections in pkvm

From: Will Deacon <will@kernel.org>
To: kvmarm@lists.cs.columbia.edu
Cc: Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	Sean Christopherson <seanjc@google.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Catalin Marinas <catalin.marinas@arm.com>,
	James Morse <james.morse@arm.com>,
	Chao Peng <chao.p.peng@linux.intel.com>,
	Quentin Perret <qperret@google.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Michael Roth <michael.roth@amd.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Fuad Tabba <tabba@google.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Marc Zyngier <maz@kernel.org>,
	kernel-team@android.com, kvm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 23/24] KVM: arm64: Don't map host sections in pkvm
Date: Thu, 30 Jun 2022 14:57:46 +0100	[thread overview]
Message-ID: <20220630135747.26983-24-will@kernel.org> (raw)
In-Reply-To: <20220630135747.26983-1-will@kernel.org>

From: Quentin Perret <qperret@google.com>

We no longer need to map the host's .rodata and .bss sections in the
pkvm hypervisor, so let's remove those mappings. This will avoid
creating dependencies at EL2 on host-controlled data-structures.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kernel/image-vars.h  |  6 ------
 arch/arm64/kvm/hyp/nvhe/setup.c | 14 +++-----------
 2 files changed, 3 insertions(+), 17 deletions(-)

diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 3e2489d23ff0..2d4d6836ff47 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -115,12 +115,6 @@ KVM_NVHE_ALIAS_HYP(__memcpy, __pi_memcpy);
 KVM_NVHE_ALIAS_HYP(__memset, __pi_memset);
 #endif
 
-/* Kernel memory sections */
-KVM_NVHE_ALIAS(__start_rodata);
-KVM_NVHE_ALIAS(__end_rodata);
-KVM_NVHE_ALIAS(__bss_start);
-KVM_NVHE_ALIAS(__bss_stop);
-
 /* Hyp memory sections */
 KVM_NVHE_ALIAS(__hyp_idmap_text_start);
 KVM_NVHE_ALIAS(__hyp_idmap_text_end);
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index fa06828899e1..1a2e06760c41 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -144,23 +144,15 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
 	}
 
 	/*
-	 * Map the host's .bss and .rodata sections RO in the hypervisor, but
-	 * transfer the ownership from the host to the hypervisor itself to
-	 * make sure it can't be donated or shared with another entity.
+	 * Map the host sections RO in the hypervisor, but transfer the
+	 * ownership from the host to the hypervisor itself to make sure they
+	 * can't be donated or shared with another entity.
 	 *
 	 * The ownership transition requires matching changes in the host
 	 * stage-2. This will be done later (see finalize_host_mappings()) once
 	 * the hyp_vmemmap is addressable.
 	 */
 	prot = pkvm_mkstate(PAGE_HYP_RO, PKVM_PAGE_SHARED_OWNED);
-	ret = pkvm_create_mappings(__start_rodata, __end_rodata, prot);
-	if (ret)
-		return ret;
-
-	ret = pkvm_create_mappings(__hyp_bss_end, __bss_stop, prot);
-	if (ret)
-		return ret;
-
 	ret = pkvm_create_mappings(&kvm_vgic_global_state,
 				   &kvm_vgic_global_state + 1, prot);
 	if (ret)
-- 
2.37.0.rc0.161.g10f37bed90-goog


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