linux-kernel - [PATCH 6/6] KVM: arm64: Unconditionally cross check hyp state

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20250227003310.367350-7-qperret@google.com>
Date: Thu, 27 Feb 2025 00:33:10 +0000
From: Quentin Perret <qperret@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>
Cc: Vincent Donnefort <vdonnefort@...gle.com>, Quentin Perret <qperret@...gle.com>, 
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	linux-kernel@...r.kernel.org
Subject: [PATCH 6/6] KVM: arm64: Unconditionally cross check hyp state

Now that the hypervisor's state is stored in the hyp_vmemmap, we no
longer need an expensive page-table walk to read it. This means we can
now afford to cross check the hyp-state during all memory ownership
transitions where the hyp is involved unconditionally, hence avoiding
problems such as [1].

[1] https://lore.kernel.org/kvmarm/20241128154406.602875-1-qperret@google.com/

Signed-off-by: Quentin Perret <qperret@...gle.com>
---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index ae39d74be1f2..22a906c7973a 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -695,11 +695,9 @@ int __pkvm_host_share_hyp(u64 pfn)
 	ret = __host_check_page_state_range(phys, size, PKVM_PAGE_OWNED);
 	if (ret)
 		goto unlock;
-	if (IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) {
-		ret = __hyp_check_page_state_range(phys, size, PKVM_NOPAGE);
-		if (ret)
-			goto unlock;
-	}
+	ret = __hyp_check_page_state_range(phys, size, PKVM_NOPAGE);
+	if (ret)
+		goto unlock;
 
 	__hyp_set_page_state_range(phys, size, PKVM_PAGE_SHARED_BORROWED);
 	WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED));
@@ -755,11 +753,9 @@ int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages)
 	ret = __host_check_page_state_range(phys, size, PKVM_PAGE_OWNED);
 	if (ret)
 		goto unlock;
-	if (IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) {
-		ret = __hyp_check_page_state_range(phys, size, PKVM_NOPAGE);
-		if (ret)
-			goto unlock;
-	}
+	ret = __hyp_check_page_state_range(phys, size, PKVM_NOPAGE);
+	if (ret)
+		goto unlock;
 
 	__hyp_set_page_state_range(phys, size, PKVM_PAGE_OWNED);
 	WARN_ON(pkvm_create_mappings_locked(virt, virt + size, PAGE_HYP));
@@ -785,11 +781,9 @@ int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages)
 	ret = __hyp_check_page_state_range(phys, size, PKVM_PAGE_OWNED);
 	if (ret)
 		goto unlock;
-	if (IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) {
-		ret = __host_check_page_state_range(phys, size, PKVM_NOPAGE);
-		if (ret)
-			goto unlock;
-	}
+	ret = __host_check_page_state_range(phys, size, PKVM_NOPAGE);
+	if (ret)
+		goto unlock;
 
 	__hyp_set_page_state_range(phys, size, PKVM_NOPAGE);
 	WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, virt, size) != size);
-- 
2.48.1.658.g4767266eb4-goog