KVM: arm64: Remove exclusive pin from memory shared by a guest
When a protected guest shares a page, remove the exclusive pin,
but maintain a normal pin on the page.
Signed-off-by: Fuad Tabba <tabba@google.com>
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 4851ce1..66e1019 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1331,6 +1331,8 @@ struct kvm *kvm_arch_alloc_vm(void);
#define vcpu_is_protected(vcpu) kvm_vm_is_protected((vcpu)->kvm)
+int pkvm_handle_guest_share(struct kvm *kvm, gfn_t gfn);
+
int kvm_arm_vcpu_finalize(struct kvm_vcpu *vcpu, int feature);
bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index b08e181..11a2c2d 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -144,23 +144,24 @@ static bool kvm_smccc_test_fw_bmap(struct kvm_vcpu *vcpu, u32 func_id)
}
}
-static int kvm_vcpu_exit_hcall(struct kvm_vcpu *vcpu, u32 nr, u32 nr_args)
+static int kvm_vcpu_handle_xshare(struct kvm_vcpu *vcpu, u32 nr)
{
- u64 mask = vcpu->kvm->arch.hypercall_exit_enabled;
- u32 i;
+ u64 mask = BIT(ARM_SMCCC_KVM_FUNC_MEM_SHARE)|BIT(ARM_SMCCC_KVM_FUNC_MEM_UNSHARE);
+ gfn_t gfn = vcpu_get_reg(vcpu, 1) >> PAGE_SHIFT;
- if (nr_args > 6 || !(mask & BIT(nr))) {
- smccc_set_retval(vcpu, SMCCC_RET_INVALID_PARAMETER, 0, 0, 0);
- return 1;
+ if (!(mask & BIT(nr)))
+ goto err;
+
+ if (nr == ARM_SMCCC_KVM_FUNC_MEM_SHARE) {
+ if (pkvm_handle_guest_share(vcpu->kvm, gfn))
+ goto err;
}
- vcpu->run->exit_reason = KVM_EXIT_HYPERCALL;
- vcpu->run->hypercall.nr = nr;
-
- for (i = 0; i < nr_args; ++i)
- vcpu->run->hypercall.args[i] = vcpu_get_reg(vcpu, i + 1);
-
return 0;
+
+err:
+ smccc_set_retval(vcpu, SMCCC_RET_INVALID_PARAMETER, 0, 0, 0);
+ return 1;
}
#define SMC32_ARCH_RANGE_BEGIN ARM_SMCCC_VERSION_FUNC_ID
@@ -411,9 +412,9 @@ int kvm_smccc_call_handler(struct kvm_vcpu *vcpu)
val[0] = SMCCC_RET_SUCCESS;
break;
case ARM_SMCCC_VENDOR_HYP_KVM_MEM_SHARE_FUNC_ID:
- return kvm_vcpu_exit_hcall(vcpu, ARM_SMCCC_KVM_FUNC_MEM_SHARE, 3);
+ return kvm_vcpu_handle_xshare(vcpu, ARM_SMCCC_KVM_FUNC_MEM_SHARE);
case ARM_SMCCC_VENDOR_HYP_KVM_MEM_UNSHARE_FUNC_ID:
- return kvm_vcpu_exit_hcall(vcpu, ARM_SMCCC_KVM_FUNC_MEM_UNSHARE, 3);
+ return kvm_vcpu_handle_xshare(vcpu, ARM_SMCCC_KVM_FUNC_MEM_UNSHARE);
case ARM_SMCCC_TRNG_VERSION:
case ARM_SMCCC_TRNG_FEATURES:
case ARM_SMCCC_TRNG_GET_UUID:
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 2d12b3c..482f251 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1434,6 +1434,53 @@ static int insert_ppage(struct kvm *kvm, struct kvm_guest_page *ppage)
return 0;
}
+static int cmp_ppages_gfn(const void *key, const struct rb_node *node)
+{
+ struct kvm_guest_page *p = container_of(node, struct kvm_guest_page, node);
+ gfn_t gfn = (gfn_t)key;
+
+ return (gfn < p->gfn) ? -1 : (gfn > p->gfn);
+}
+
+static struct kvm_guest_page *find_page(struct kvm *kvm, gfn_t gfn)
+{
+ struct rb_node *node;
+
+ node = rb_find((void *)gfn, &kvm->arch.pkvm.pinned_pages, cmp_ppages_gfn);
+
+ if (!node)
+ return NULL;
+
+ return container_of(node, struct kvm_guest_page, node);
+}
+
+int pkvm_handle_guest_share(struct kvm *kvm, gfn_t gfn)
+{
+ struct kvm_guest_page *ppage;
+ int ret = 0;
+
+ write_lock(&kvm->mmu_lock);
+
+ ppage = find_page(kvm, gfn);
+
+ if (WARN_ON(!ppage)) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ if (WARN_ON(!ppage->is_private)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ unexc_user_page(ppage->page);
+ ppage->is_private = false;
+out:
+ write_unlock(&kvm->mmu_lock);
+
+ return ret;
+}
+
static int pkvm_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
struct kvm_memory_slot *memslot)
{
