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KVM: arm64: Introduce __pkvm_host_unshare_guest()

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In preparation for letting the host unmap pages from non-protected
guests, introduce a new hypercall implementing the host-unshare-guest
transition.

Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20241218194059.3670226-12-qperret@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Quentin Perret
2024-12-18 19:40:52 +00:00
committed by Marc Zyngier
parent d0bd3e6570
commit 72db3d3fba
6 changed files with 108 additions and 0 deletions
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1
arch/arm64/include/asm/kvm_asm.h
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@@ -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,

1
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
View File

@@ -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);
bool addr_is_memory(phys_addr_t phys);
int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot);

6
arch/arm64/kvm/hyp/include/nvhe/pkvm.h
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@@ -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,
@@ -78,6 +83,7 @@ void pkvm_put_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu);
struct pkvm_hyp_vcpu *pkvm_get_loaded_hyp_vcpu(void);
struct pkvm_hyp_vm *get_pkvm_hyp_vm(pkvm_handle_t handle);
struct pkvm_hyp_vm *get_np_pkvm_hyp_vm(pkvm_handle_t handle);
void put_pkvm_hyp_vm(struct pkvm_hyp_vm *hyp_vm);
#endif /* __ARM64_KVM_NVHE_PKVM_H__ */

21
arch/arm64/kvm/hyp/nvhe/hyp-main.c
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@@ -244,6 +244,26 @@ out:
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_np_pkvm_hyp_vm(handle);
if (!hyp_vm)
goto out;
ret = __pkvm_host_unshare_guest(gfn, 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);
@@ -454,6 +474,7 @@ 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),

67
arch/arm64/kvm/hyp/nvhe/mem_protect.c
View File

@@ -1421,3 +1421,70 @@ unlock:
return ret;
}
static int __check_host_shared_guest(struct pkvm_hyp_vm *vm, u64 *__phys, u64 ipa)
{
enum pkvm_page_state state;
struct hyp_page *page;
kvm_pte_t pte;
u64 phys;
s8 level;
int ret;
ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level);
if (ret)
return ret;
if (level != KVM_PGTABLE_LAST_LEVEL)
return -E2BIG;
if (!kvm_pte_valid(pte))
return -ENOENT;
state = guest_get_page_state(pte, ipa);
if (state != PKVM_PAGE_SHARED_BORROWED)
return -EPERM;
phys = kvm_pte_to_phys(pte);
ret = check_range_allowed_memory(phys, phys + PAGE_SIZE);
if (WARN_ON(ret))
return ret;
page = hyp_phys_to_page(phys);
if (page->host_state != PKVM_PAGE_SHARED_OWNED)
return -EPERM;
if (WARN_ON(!page->host_share_guest_count))
return -EINVAL;
*__phys = phys;
return 0;
}
int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *vm)
{
u64 ipa = hyp_pfn_to_phys(gfn);
struct hyp_page *page;
u64 phys;
int ret;
host_lock_component();
guest_lock_component(vm);
ret = __check_host_shared_guest(vm, &phys, ipa);
if (ret)
goto unlock;
ret = kvm_pgtable_stage2_unmap(&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(vm);
host_unlock_component();
return ret;
}

12
arch/arm64/kvm/hyp/nvhe/pkvm.c
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@@ -376,6 +376,18 @@ void put_pkvm_hyp_vm(struct pkvm_hyp_vm *hyp_vm)
hyp_spin_unlock(&vm_table_lock);
}
struct pkvm_hyp_vm *get_np_pkvm_hyp_vm(pkvm_handle_t handle)
{
struct pkvm_hyp_vm *hyp_vm = get_pkvm_hyp_vm(handle);
if (hyp_vm && pkvm_hyp_vm_is_protected(hyp_vm)) {
put_pkvm_hyp_vm(hyp_vm);
hyp_vm = NULL;
}
return hyp_vm;
}
static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struct kvm *host_kvm)
{
struct kvm *kvm = &hyp_vm->kvm;