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Message-ID: <20241104133204.85208-13-qperret@google.com>
Date: Mon, 4 Nov 2024 13:31:58 +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 12/18] KVM: arm64: Introduce __pkvm_host_relax_guest_perms()
Introduce a new hypercall allowing the host to relax the stage-2
permissions of mappings in a non-protected guest page-table. It will be
used later once we start allowing RO memslots and dirty logging.
Signed-off-by: Quentin Perret <qperret@...gle.com>
---
arch/arm64/include/asm/kvm_asm.h | 1 +
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 1 +
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 20 +++++++++++++++
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 25 +++++++++++++++++++
4 files changed, 47 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index e67efee936b6..f528656e8359 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -67,6 +67,7 @@ enum __kvm_host_smccc_func {
__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp,
__KVM_HOST_SMCCC_FUNC___pkvm_host_share_guest,
__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_guest,
+ __KVM_HOST_SMCCC_FUNC___pkvm_host_relax_guest_perms,
__KVM_HOST_SMCCC_FUNC___kvm_adjust_pc,
__KVM_HOST_SMCCC_FUNC___kvm_vcpu_run,
__KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context,
diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index e528a42ed60e..db0dd83c2457 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -41,6 +41,7 @@ int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages);
int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);
int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu, enum kvm_pgtable_prot prot);
int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm);
+int __pkvm_host_relax_guest_perms(u64 gfn, enum kvm_pgtable_prot prot, struct pkvm_hyp_vcpu *vcpu);
bool addr_is_memory(phys_addr_t phys);
int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot);
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 68bbef69d99a..d3210719e247 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -265,6 +265,25 @@ static void handle___pkvm_host_unshare_guest(struct kvm_cpu_context *host_ctxt)
cpu_reg(host_ctxt, 1) = ret;
}
+static void handle___pkvm_host_relax_guest_perms(struct kvm_cpu_context *host_ctxt)
+{
+ DECLARE_REG(u64, gfn, host_ctxt, 1);
+ DECLARE_REG(enum kvm_pgtable_prot, prot, host_ctxt, 2);
+ struct pkvm_hyp_vcpu *hyp_vcpu;
+ int ret = -EINVAL;
+
+ if (!is_protected_kvm_enabled())
+ goto out;
+
+ hyp_vcpu = pkvm_get_loaded_hyp_vcpu();
+ if (!hyp_vcpu || pkvm_hyp_vcpu_is_protected(hyp_vcpu))
+ goto out;
+
+ ret = __pkvm_host_relax_guest_perms(gfn, prot, hyp_vcpu);
+out:
+ cpu_reg(host_ctxt, 1) = ret;
+}
+
static void handle___kvm_adjust_pc(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(struct kvm_vcpu *, vcpu, host_ctxt, 1);
@@ -483,6 +502,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__pkvm_host_unshare_hyp),
HANDLE_FUNC(__pkvm_host_share_guest),
HANDLE_FUNC(__pkvm_host_unshare_guest),
+ HANDLE_FUNC(__pkvm_host_relax_guest_perms),
HANDLE_FUNC(__kvm_adjust_pc),
HANDLE_FUNC(__kvm_vcpu_run),
HANDLE_FUNC(__kvm_flush_vm_context),
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index f7476a29e1a9..fc6050dcf904 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -1491,3 +1491,28 @@ int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm)
return ret;
}
+
+int __pkvm_host_relax_guest_perms(u64 gfn, enum kvm_pgtable_prot prot, struct pkvm_hyp_vcpu *vcpu)
+{
+ struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
+ u64 ipa = hyp_pfn_to_phys(gfn);
+ u64 phys;
+ int ret;
+
+ if ((prot & KVM_PGTABLE_PROT_RWX) != prot)
+ return -EPERM;
+
+ host_lock_component();
+ guest_lock_component(vm);
+
+ ret = __check_host_unshare_guest(vm, &phys, ipa);
+ if (ret)
+ goto unlock;
+
+ ret = kvm_pgtable_stage2_relax_perms(&vm->pgt, ipa, prot, 0);
+unlock:
+ guest_unlock_component(vm);
+ host_unlock_component();
+
+ return ret;
+}
--
2.47.0.163.g1226f6d8fa-goog
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