linux-kernel - [PATCH v5 31/43] arm64: rme: Prevent Device mappings for Realms

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Message-Id: <20241004152804.72508-32-steven.price@arm.com>
Date: Fri,  4 Oct 2024 16:27:52 +0100
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Steven Price <steven.price@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>,
	Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>,
	linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@...nel.org>
Subject: [PATCH v5 31/43] arm64: rme: Prevent Device mappings for Realms

Physical device assignment is not yet supported by the RMM, so it
doesn't make much sense to allow device mappings within the realm.
Prevent them when the guest is a realm.

Signed-off-by: Steven Price <steven.price@....com>
---
 arch/arm64/kvm/mmu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 4f0403059c91..602c49eae90d 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1142,6 +1142,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
 	if (is_protected_kvm_enabled())
 		return -EPERM;
 
+	/* We don't support mapping special pages into a Realm */
+	if (kvm_is_realm(kvm))
+		return -EINVAL;
+
 	size += offset_in_page(guest_ipa);
 	guest_ipa &= PAGE_MASK;
 
-- 
2.34.1