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Message-ID: <20241104133204.85208-17-qperret@google.com>
Date: Mon, 4 Nov 2024 13:32:02 +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: Fuad Tabba <tabba@...gle.com>, Vincent Donnefort <vdonnefort@...gle.com>,
Sebastian Ene <sebastianene@...gle.com>, linux-arm-kernel@...ts.infradead.org,
kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH 16/18] KVM: arm64: Introduce __pkvm_tlb_flush_vmid()
Introduce a new hypercall to flush the TLBs of non-protected guests. The
host kernel will be responsible for issuing this hypercall after changing
stage-2 permissions using the __pkvm_host_relax_guest_perms() or
__pkvm_host_wrprotect_guest() paths. This is left under the host's
responsibility for performance reasons.
Note however that the TLB maintenance for all *unmap* operations still
remains entirely under the hypervisor's responsibility for security
reasons -- an unmapped page may be donated to another entity, so a stale
TLB entry could be used to leak private data.
Signed-off-by: Quentin Perret <qperret@...gle.com>
---
arch/arm64/include/asm/kvm_asm.h | 1 +
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 17 +++++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 4b93fb3a9a96..1bf7bc51f50f 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -88,6 +88,7 @@ enum __kvm_host_smccc_func {
__KVM_HOST_SMCCC_FUNC___pkvm_teardown_vm,
__KVM_HOST_SMCCC_FUNC___pkvm_vcpu_load,
__KVM_HOST_SMCCC_FUNC___pkvm_vcpu_put,
+ __KVM_HOST_SMCCC_FUNC___pkvm_tlb_flush_vmid,
};
#define DECLARE_KVM_VHE_SYM(sym) extern char sym[]
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 904f6b1edced..1d8baa14ff1c 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -396,6 +396,22 @@ static void handle___kvm_tlb_flush_vmid(struct kvm_cpu_context *host_ctxt)
__kvm_tlb_flush_vmid(kern_hyp_va(mmu));
}
+static void handle___pkvm_tlb_flush_vmid(struct kvm_cpu_context *host_ctxt)
+{
+ DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);
+ struct pkvm_hyp_vm *hyp_vm;
+
+ if (!is_protected_kvm_enabled())
+ return;
+
+ hyp_vm = get_pkvm_hyp_vm(handle);
+ if (!hyp_vm)
+ return;
+
+ __kvm_tlb_flush_vmid(&hyp_vm->kvm.arch.mmu);
+ put_pkvm_hyp_vm(hyp_vm);
+}
+
static void handle___kvm_flush_cpu_context(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(struct kvm_s2_mmu *, mmu, host_ctxt, 1);
@@ -588,6 +604,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__pkvm_teardown_vm),
HANDLE_FUNC(__pkvm_vcpu_load),
HANDLE_FUNC(__pkvm_vcpu_put),
+ HANDLE_FUNC(__pkvm_tlb_flush_vmid),
};
static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
--
2.47.0.163.g1226f6d8fa-goog
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