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From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Marc Zyngier <maz@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu
Subject: [PATCH v2 4/5] KVM: arm64: Prevent re-finalisation of pKVM for a given CPU
Date: Tue,  5 Oct 2021 12:37:20 +0100	[thread overview]
Message-ID: <20211005113721.29441-5-will@kernel.org> (raw)
In-Reply-To: <20211005113721.29441-1-will@kernel.org>

__pkvm_prot_finalize() completes the deprivilege of the host when pKVM
is in use by installing a stage-2 translation table for the calling CPU.

Issuing the hypercall multiple times for a given CPU makes little sense,
but in such a case just return early with -EPERM rather than go through
the whole page-table dance again.

Cc: Marc Zyngier <maz@kernel.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index bacd493a4eac..cafe17e5fa8f 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -123,6 +123,9 @@ int __pkvm_prot_finalize(void)
 	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
 	struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
 
+	if (params->hcr_el2 & HCR_VM)
+		return -EPERM;
+
 	params->vttbr = kvm_get_vttbr(mmu);
 	params->vtcr = host_kvm.arch.vtcr;
 	params->hcr_el2 |= HCR_VM;
-- 
2.33.0.800.g4c38ced690-goog

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Quentin Perret <qperret@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	kvmarm@lists.cs.columbia.edu
Subject: [PATCH v2 4/5] KVM: arm64: Prevent re-finalisation of pKVM for a given CPU
Date: Tue,  5 Oct 2021 12:37:20 +0100	[thread overview]
Message-ID: <20211005113721.29441-5-will@kernel.org> (raw)
In-Reply-To: <20211005113721.29441-1-will@kernel.org>

__pkvm_prot_finalize() completes the deprivilege of the host when pKVM
is in use by installing a stage-2 translation table for the calling CPU.

Issuing the hypercall multiple times for a given CPU makes little sense,
but in such a case just return early with -EPERM rather than go through
the whole page-table dance again.

Cc: Marc Zyngier <maz@kernel.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index bacd493a4eac..cafe17e5fa8f 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -123,6 +123,9 @@ int __pkvm_prot_finalize(void)
 	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
 	struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
 
+	if (params->hcr_el2 & HCR_VM)
+		return -EPERM;
+
 	params->vttbr = kvm_get_vttbr(mmu);
 	params->vtcr = host_kvm.arch.vtcr;
 	params->hcr_el2 |= HCR_VM;
-- 
2.33.0.800.g4c38ced690-goog


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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-10-05 11:37 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-05 11:37 [PATCH v2 0/5] KVM: arm64: Restrict host hypercalls when pKVM is enabled Will Deacon
2021-10-05 11:37 ` Will Deacon
2021-10-05 11:37 ` [PATCH v2 1/5] arm64: Prevent kexec and hibernation if is_protected_kvm_enabled() Will Deacon
2021-10-05 11:37   ` Will Deacon
2021-10-05 11:37 ` [PATCH v2 2/5] KVM: arm64: Reject stub hypercalls after pKVM has been initialised Will Deacon
2021-10-05 11:37   ` Will Deacon
2021-10-05 11:37 ` [PATCH v2 3/5] KVM: arm64: Propagate errors from __pkvm_prot_finalize hypercall Will Deacon
2021-10-05 11:37   ` Will Deacon
2021-10-05 11:37 ` Will Deacon [this message]
2021-10-05 11:37   ` [PATCH v2 4/5] KVM: arm64: Prevent re-finalisation of pKVM for a given CPU Will Deacon
2021-10-05 11:37 ` [PATCH v2 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation Will Deacon
2021-10-05 11:37   ` Will Deacon
2021-10-07 12:56   ` Marc Zyngier
2021-10-07 12:56     ` Marc Zyngier
2021-10-08  7:27     ` Will Deacon
2021-10-08  7:27       ` Will Deacon
2021-10-08  7:31       ` Marc Zyngier
2021-10-08  7:31         ` Marc Zyngier

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