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Message-ID: <20241104133204.85208-12-qperret@google.com>
Date: Mon, 4 Nov 2024 13:31:57 +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 11/18] KVM: arm64: Introduce __pkvm_host_unshare_guest()
In preparation for letting the host unmap pages from non-protected
guests, introduce a new hypercall implementing the host-unshare-guest
transition.
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/include/nvhe/pkvm.h | 5 ++
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 24 ++++++
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 78 +++++++++++++++++++
5 files changed, 109 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index b69390108c5a..e67efee936b6 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -66,6 +66,7 @@ enum __kvm_host_smccc_func {
__KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,
__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___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 a7976e50f556..e528a42ed60e 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -40,6 +40,7 @@ int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
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);
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/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
index be52c5b15e21..5dfc9ece9aa5 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
@@ -64,6 +64,11 @@ static inline bool pkvm_hyp_vcpu_is_protected(struct pkvm_hyp_vcpu *hyp_vcpu)
return vcpu_is_protected(&hyp_vcpu->vcpu);
}
+static inline bool pkvm_hyp_vm_is_protected(struct pkvm_hyp_vm *hyp_vm)
+{
+ return kvm_vm_is_protected(&hyp_vm->kvm);
+}
+
void pkvm_hyp_vm_table_init(void *tbl);
int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva,
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 32bdf6b27958..68bbef69d99a 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -242,6 +242,29 @@ static void handle___pkvm_host_share_guest(struct kvm_cpu_context *host_ctxt)
cpu_reg(host_ctxt, 1) = ret;
}
+static void handle___pkvm_host_unshare_guest(struct kvm_cpu_context *host_ctxt)
+{
+ DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);
+ DECLARE_REG(u64, gfn, host_ctxt, 2);
+ struct pkvm_hyp_vm *hyp_vm;
+ int ret = -EINVAL;
+
+ if (!is_protected_kvm_enabled())
+ goto out;
+
+ hyp_vm = get_pkvm_hyp_vm(handle);
+ if (!hyp_vm)
+ goto out;
+ if (pkvm_hyp_vm_is_protected(hyp_vm))
+ goto put_hyp_vm;
+
+ ret = __pkvm_host_unshare_guest(gfn, hyp_vm);
+put_hyp_vm:
+ put_pkvm_hyp_vm(hyp_vm);
+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);
@@ -459,6 +482,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__pkvm_host_share_hyp),
HANDLE_FUNC(__pkvm_host_unshare_hyp),
HANDLE_FUNC(__pkvm_host_share_guest),
+ HANDLE_FUNC(__pkvm_host_unshare_guest),
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 a69d7212b64c..f7476a29e1a9 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -1413,3 +1413,81 @@ int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu,
return ret;
}
+
+static int guest_get_valid_pte(struct pkvm_hyp_vm *vm, u64 *phys, u64 ipa, u8 order, kvm_pte_t *pte)
+{
+ size_t size = PAGE_SIZE << order;
+ s8 level;
+
+ if (order && size != PMD_SIZE)
+ return -EINVAL;
+
+ WARN_ON(kvm_pgtable_get_leaf(&vm->pgt, ipa, pte, &level));
+
+ if (kvm_granule_size(level) != size)
+ return -E2BIG;
+
+ if (!kvm_pte_valid(*pte))
+ return -ENOENT;
+
+ *phys = kvm_pte_to_phys(*pte);
+
+ return 0;
+}
+
+static int __check_host_unshare_guest(struct pkvm_hyp_vm *vm, u64 *phys, u64 ipa)
+{
+ enum pkvm_page_state state;
+ struct hyp_page *page;
+ kvm_pte_t pte;
+ int ret;
+
+ ret = guest_get_valid_pte(vm, phys, ipa, 0, &pte);
+ if (ret)
+ return ret;
+
+ state = guest_get_page_state(pte, ipa);
+ if (state != PKVM_PAGE_SHARED_BORROWED)
+ return -EPERM;
+
+ ret = range_is_allowed_memory(*phys, *phys + PAGE_SIZE);
+ if (ret)
+ return ret;
+
+ page = hyp_phys_to_page(*phys);
+ if (page->host_state != PKVM_PAGE_SHARED_OWNED)
+ return -EPERM;
+ WARN_ON(!page->host_share_guest_count);
+
+ return 0;
+}
+
+int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm)
+{
+ u64 ipa = hyp_pfn_to_phys(gfn);
+ struct hyp_page *page;
+ u64 phys;
+ int ret;
+
+ host_lock_component();
+ guest_lock_component(hyp_vm);
+
+ ret = __check_host_unshare_guest(hyp_vm, &phys, ipa);
+ if (ret)
+ goto unlock;
+
+ ret = kvm_pgtable_stage2_unmap(&hyp_vm->pgt, ipa, PAGE_SIZE);
+ if (ret)
+ goto unlock;
+
+ page = hyp_phys_to_page(phys);
+ page->host_share_guest_count--;
+ if (!page->host_share_guest_count)
+ WARN_ON(__host_set_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_OWNED));
+
+unlock:
+ guest_unlock_component(hyp_vm);
+ host_unlock_component();
+
+ return ret;
+}
--
2.47.0.163.g1226f6d8fa-goog
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