Re: [PATCH v1 11/11] KVM: arm64: Tag host-VA hypercall parameters __hostva
Vincent Donnefort <[email protected]> Mon, 3 Aug 2026 11:50:38 +0100
| Newsgroups | org.kernel.vger.linux-trace-kernel,dev.linux.lists.kvmarm,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
On Mon, Jul 20, 2026 at 05:24:12PM +0100, Fuad Tabba wrote: > The nVHE hypervisor takes host virtual addresses as hypercall arguments > and translates each with kern_hyp_va() before use. Nothing marks them as > host-owned, so dereferencing one untranslated at EL2 - a recurring bug > class - is invisible to the compiler. > > Add a __hostva sparse address space, active only for EL2 code, and tag > the host-VA parameters in the hypercall declarations. kern_hyp_va_host() > is the only sanctioned unwrap: it translates the address, preserves the > pointee type (stripped of qualifiers, as with the percpu accessors) and > drops the tag with a __force cast, so an untranslated host VA fails > sparse. The tag flows from the shared declaration into the generated > handler and on into the donated-memory and tracing-descriptor helpers, > so a handler cannot extract a host VA without it. Host code sees plain > pointers, and the tag is checker-only: no code is generated. > > Signed-off-by: Fuad Tabba <[email protected]> > --- > arch/arm64/include/asm/kvm_hcall.h | 43 ++++++++++++------- > arch/arm64/include/asm/kvm_mmu.h | 10 +++++ > arch/arm64/kvm/hyp/include/nvhe/pkvm.h | 6 ++- > arch/arm64/kvm/hyp/include/nvhe/trace.h | 5 ++- > arch/arm64/kvm/hyp/nvhe/hyp-main.c | 57 +++++++++++++------------ > arch/arm64/kvm/hyp/nvhe/pkvm.c | 11 ++--- > arch/arm64/kvm/hyp/nvhe/trace.c | 4 +- > 7 files changed, 82 insertions(+), 54 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_hcall.h b/arch/arm64/include/asm/kvm_hcall.h > index 6aa2df90a14a4..3033a6ba1462a 100644 > --- a/arch/arm64/include/asm/kvm_hcall.h > +++ b/arch/arm64/include/asm/kvm_hcall.h > @@ -27,6 +27,18 @@ struct kvm_vcpu; > struct vgic_v3_cpu_if; > struct vgic_v5_cpu_if; > > +/* > + * A host VA carried by a hypercall argument. At EL2 such a pointer must not > + * be dereferenced until it is translated with kern_hyp_va_host(); sparse > + * flags any use that skips the translation. The tag describes the EL2 view > + * only: the host dereferences its own VAs freely. > + */ > +#if defined(__KVM_NVHE_HYPERVISOR__) && defined(__CHECKER__) > +#define __hostva __attribute__((noderef, address_space(__hostva))) > +#else > +#define __hostva > +#endif Could we have __kern, just like we have __user. Ideally this could be used later to mark the values we don't trust, so not only VAs but also nr_pages. In mem_protect.c e.g. size_t pfn_range_is_valid(u64 __kern pfn, u64 __kern nr_pages) so that size is only trusted once pfn_range_is_valid() has run. And beside, that matches "kern_hyp_va" > + > /* > * Hypercall signatures are declared as (type, name) argument pairs. > * __KVM_HCALL_MAP() applies a macro to each pair, in the mold of __MAP() > @@ -157,24 +169,24 @@ DECLARE_KVM_HOST_HCALL0(int, __pkvm_prot_finalize) > > /* Hypercalls that are always available and common to [nh]VHE/pKVM. */ > DECLARE_KVM_HOST_HCALL_VOID(__kvm_adjust_pc, 1, > - struct kvm_vcpu *, vcpu) > + struct kvm_vcpu __hostva *, vcpu) > DECLARE_KVM_HOST_HCALL(int, __kvm_vcpu_run, 1, > - struct kvm_vcpu *, vcpu) > + struct kvm_vcpu __hostva *, vcpu) > DECLARE_KVM_HOST_HCALL0_VOID(__kvm_flush_vm_context) > DECLARE_KVM_HOST_HCALL_VOID(__kvm_tlb_flush_vmid_ipa, 3, > - struct kvm_s2_mmu *, mmu, phys_addr_t, ipa, int, level) > + struct kvm_s2_mmu __hostva *, mmu, phys_addr_t, ipa, int, level) > DECLARE_KVM_HOST_HCALL_VOID(__kvm_tlb_flush_vmid_ipa_nsh, 3, > - struct kvm_s2_mmu *, mmu, phys_addr_t, ipa, int, level) > + struct kvm_s2_mmu __hostva *, mmu, phys_addr_t, ipa, int, level) > DECLARE_KVM_HOST_HCALL_VOID(__kvm_tlb_flush_vmid, 1, > - struct kvm_s2_mmu *, mmu) > + struct kvm_s2_mmu __hostva *, mmu) > DECLARE_KVM_HOST_HCALL_VOID(__kvm_tlb_flush_vmid_range, 3, > - struct kvm_s2_mmu *, mmu, phys_addr_t, start, unsigned long, pages) > + struct kvm_s2_mmu __hostva *, mmu, phys_addr_t, start, unsigned long, pages) > DECLARE_KVM_HOST_HCALL_VOID(__kvm_flush_cpu_context, 1, > - struct kvm_s2_mmu *, mmu) > + struct kvm_s2_mmu __hostva *, mmu) > DECLARE_KVM_HOST_HCALL_VOID(__kvm_timer_set_cntvoff, 1, > u64, cntvoff) > DECLARE_KVM_HOST_HCALL(int, __tracing_load, 2, > - void *, desc_hva, size_t, desc_size) > + void __hostva *, desc_hva, size_t, desc_size) > DECLARE_KVM_HOST_HCALL0_VOID(__tracing_unload) > DECLARE_KVM_HOST_HCALL(int, __tracing_enable, 1, > bool, enable) > @@ -189,13 +201,13 @@ DECLARE_KVM_HOST_HCALL(int, __tracing_enable_event, 2, > DECLARE_KVM_HOST_HCALL_VOID(__tracing_write_event, 1, > u64, id) > DECLARE_KVM_HOST_HCALL_VOID(__vgic_v3_save_aprs, 1, > - struct vgic_v3_cpu_if *, cpu_if) > + struct vgic_v3_cpu_if __hostva *, cpu_if) > DECLARE_KVM_HOST_HCALL_VOID(__vgic_v3_restore_vmcr_aprs, 1, > - struct vgic_v3_cpu_if *, cpu_if) > + struct vgic_v3_cpu_if __hostva *, cpu_if) > DECLARE_KVM_HOST_HCALL_VOID(__vgic_v5_save_apr, 1, > - struct vgic_v5_cpu_if *, cpu_if) > + struct vgic_v5_cpu_if __hostva *, cpu_if) > DECLARE_KVM_HOST_HCALL_VOID(__vgic_v5_restore_vmcr_apr, 1, > - struct vgic_v5_cpu_if *, cpu_if) > + struct vgic_v5_cpu_if __hostva *, cpu_if) > > /* Hypercalls that are available only when pKVM has finalised. */ > DECLARE_KVM_HOST_HCALL(int, __pkvm_host_share_hyp, 1, > @@ -220,10 +232,11 @@ DECLARE_KVM_HOST_HCALL0(int, __pkvm_reserve_vm) > DECLARE_KVM_HOST_HCALL_VOID(__pkvm_unreserve_vm, 1, > pkvm_handle_t, handle) > DECLARE_KVM_HOST_HCALL(int, __pkvm_init_vm, 3, > - struct kvm *, host_kvm, void *, vm_hva, void *, pgd_hva) > + struct kvm __hostva *, host_kvm, void __hostva *, vm_hva, > + void __hostva *, pgd_hva) > DECLARE_KVM_HOST_HCALL(int, __pkvm_init_vcpu, 3, > - pkvm_handle_t, handle, struct kvm_vcpu *, host_vcpu, > - void *, vcpu_hva) > + pkvm_handle_t, handle, struct kvm_vcpu __hostva *, host_vcpu, > + void __hostva *, vcpu_hva) > DECLARE_KVM_HOST_HCALL0(int, __pkvm_vcpu_in_poison_fault) > DECLARE_KVM_HOST_HCALL(int, __pkvm_force_reclaim_guest_page, 1, > phys_addr_t, phys) > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h > index 6eae7e7e2a684..55fac40377c03 100644 > --- a/arch/arm64/include/asm/kvm_mmu.h > +++ b/arch/arm64/include/asm/kvm_mmu.h > @@ -7,6 +7,8 @@ > #ifndef __ARM64_KVM_MMU_H__ > #define __ARM64_KVM_MMU_H__ > > +#include <linux/compiler.h> > + > #include <asm/page.h> > #include <asm/memory.h> > #include <asm/mmu.h> > @@ -140,6 +142,14 @@ static __always_inline unsigned long __kern_hyp_va(unsigned long v) > > #define kern_hyp_va(v) ((typeof(v))(__kern_hyp_va((unsigned long)(v)))) > > +/* > + * Translate a __hostva-tagged host VA, dropping the tag: the only sanctioned > + * unwrap. Translation only, no ownership or bounds validation; the result > + * carries the pointee type stripped of the tag and of any cv-qualifiers. > + */ > +#define kern_hyp_va_host(v) \ > + ((TYPEOF_UNQUAL(*(v)) *)__kern_hyp_va((unsigned long)(__force void *)(v))) > + > extern u32 __hyp_va_bits; > > /* > diff --git a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h > index 2643a1a819668..dcbe8b8913270 100644 > --- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h > +++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h > @@ -7,6 +7,7 @@ > #ifndef __ARM64_KVM_NVHE_PKVM_H__ > #define __ARM64_KVM_NVHE_PKVM_H__ > > +#include <asm/kvm_hcall.h> > #include <asm/kvm_pkvm.h> > > #include <nvhe/gfp.h> > @@ -69,9 +70,10 @@ void pkvm_hyp_vm_table_init(void *tbl); > > int __pkvm_reserve_vm(void); > void __pkvm_unreserve_vm(pkvm_handle_t handle); > -int __pkvm_init_vm(struct kvm *host_kvm, void *vm_hva, void *pgd_hva); > +int __pkvm_init_vm(struct kvm *host_kvm, void __hostva *vm_hva, > + void __hostva *pgd_hva); > int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu, > - void *vcpu_hva); > + void __hostva *vcpu_hva); > > int __pkvm_reclaim_dying_guest_page(pkvm_handle_t handle, u64 gfn); > int __pkvm_start_teardown_vm(pkvm_handle_t handle); > diff --git a/arch/arm64/kvm/hyp/include/nvhe/trace.h b/arch/arm64/kvm/hyp/include/nvhe/trace.h > index 4aa36fd76b9e2..58e0ad3329034 100644 > --- a/arch/arm64/kvm/hyp/include/nvhe/trace.h > +++ b/arch/arm64/kvm/hyp/include/nvhe/trace.h > @@ -4,6 +4,7 @@ > > #include <linux/trace_remote_event.h> > > +#include <asm/kvm_hcall.h> > #include <asm/kvm_hyptrace.h> > > static inline pid_t __tracing_get_vcpu_pid(struct kvm_cpu_context *host_ctxt) > @@ -46,7 +47,7 @@ static inline pid_t __tracing_get_vcpu_pid(struct kvm_cpu_context *host_ctxt) > void *tracing_reserve_entry(unsigned long length); > void tracing_commit_entry(void); > > -int __tracing_load(void *desc_va, size_t desc_size); > +int __tracing_load(void __hostva *desc_va, size_t desc_size); > void __tracing_unload(void); > int __tracing_enable(bool enable); > int __tracing_swap_reader(unsigned int cpu); > @@ -59,7 +60,7 @@ static inline void tracing_commit_entry(void) { } > #define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \ > static inline void trace_##__name(__proto) {} > > -static inline int __tracing_load(void *desc_va, size_t desc_size) { return -ENODEV; } > +static inline int __tracing_load(void __hostva *desc_va, size_t desc_size) { return -ENODEV; } > static inline void __tracing_unload(void) { } > static inline int __tracing_enable(bool enable) { return -ENODEV; } > static inline int __tracing_swap_reader(unsigned int cpu) { return -ENODEV; } > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > index f2501249f4391..679b6df9c998d 100644 > --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > @@ -269,7 +269,7 @@ DEFINE_KVM_HOST_HCALL0_VOID(__pkvm_vcpu_put) > } > > DEFINE_KVM_HOST_HCALL(int, __kvm_vcpu_run, 1, > - struct kvm_vcpu *, host_vcpu) > + struct kvm_vcpu __hostva *, host_vcpu) > { > int ret; > > @@ -294,7 +294,7 @@ DEFINE_KVM_HOST_HCALL(int, __kvm_vcpu_run, 1, > > sync_hyp_vcpu(hyp_vcpu); > } else { > - struct kvm_vcpu *vcpu = kern_hyp_va(host_vcpu); > + struct kvm_vcpu *vcpu = kern_hyp_va_host(host_vcpu); > > /* The host is fully trusted, run its vCPU directly. */ > fpsimd_lazy_switch_to_guest(vcpu); > @@ -421,9 +421,9 @@ DEFINE_KVM_HOST_HCALL(int, __pkvm_host_mkyoung_guest, 1, > } > > DEFINE_KVM_HOST_HCALL_VOID(__kvm_adjust_pc, 1, > - struct kvm_vcpu *, vcpu) > + struct kvm_vcpu __hostva *, vcpu) > { > - __kvm_adjust_pc(kern_hyp_va(vcpu)); > + __kvm_adjust_pc(kern_hyp_va_host(vcpu)); > } > > DEFINE_KVM_HOST_HCALL0_VOID(__kvm_flush_vm_context) > @@ -432,27 +432,27 @@ DEFINE_KVM_HOST_HCALL0_VOID(__kvm_flush_vm_context) > } > > DEFINE_KVM_HOST_HCALL_VOID(__kvm_tlb_flush_vmid_ipa, 3, > - struct kvm_s2_mmu *, mmu, phys_addr_t, ipa, int, level) > + struct kvm_s2_mmu __hostva *, mmu, phys_addr_t, ipa, int, level) > { > - __kvm_tlb_flush_vmid_ipa(kern_hyp_va(mmu), ipa, level); > + __kvm_tlb_flush_vmid_ipa(kern_hyp_va_host(mmu), ipa, level); > } > > DEFINE_KVM_HOST_HCALL_VOID(__kvm_tlb_flush_vmid_ipa_nsh, 3, > - struct kvm_s2_mmu *, mmu, phys_addr_t, ipa, int, level) > + struct kvm_s2_mmu __hostva *, mmu, phys_addr_t, ipa, int, level) > { > - __kvm_tlb_flush_vmid_ipa_nsh(kern_hyp_va(mmu), ipa, level); > + __kvm_tlb_flush_vmid_ipa_nsh(kern_hyp_va_host(mmu), ipa, level); > } > > DEFINE_KVM_HOST_HCALL_VOID(__kvm_tlb_flush_vmid_range, 3, > - struct kvm_s2_mmu *, mmu, phys_addr_t, start, unsigned long, pages) > + struct kvm_s2_mmu __hostva *, mmu, phys_addr_t, start, unsigned long, pages) > { > - __kvm_tlb_flush_vmid_range(kern_hyp_va(mmu), start, pages); > + __kvm_tlb_flush_vmid_range(kern_hyp_va_host(mmu), start, pages); > } > > DEFINE_KVM_HOST_HCALL_VOID(__kvm_tlb_flush_vmid, 1, > - struct kvm_s2_mmu *, mmu) > + struct kvm_s2_mmu __hostva *, mmu) > { > - __kvm_tlb_flush_vmid(kern_hyp_va(mmu)); > + __kvm_tlb_flush_vmid(kern_hyp_va_host(mmu)); > } > > DEFINE_KVM_HOST_HCALL_VOID(__pkvm_tlb_flush_vmid, 1, > @@ -468,9 +468,9 @@ DEFINE_KVM_HOST_HCALL_VOID(__pkvm_tlb_flush_vmid, 1, > } > > DEFINE_KVM_HOST_HCALL_VOID(__kvm_flush_cpu_context, 1, > - struct kvm_s2_mmu *, mmu) > + struct kvm_s2_mmu __hostva *, mmu) > { > - __kvm_flush_cpu_context(kern_hyp_va(mmu)); > + __kvm_flush_cpu_context(kern_hyp_va_host(mmu)); > } > > DEFINE_KVM_HOST_HCALL_VOID(__kvm_timer_set_cntvoff, 1, > @@ -499,15 +499,15 @@ DEFINE_KVM_HOST_HCALL0_VOID(__vgic_v3_init_lrs) > } > > DEFINE_KVM_HOST_HCALL_VOID(__vgic_v3_save_aprs, 1, > - struct vgic_v3_cpu_if *, cpu_if) > + struct vgic_v3_cpu_if __hostva *, cpu_if) > { > - __vgic_v3_save_aprs(kern_hyp_va(cpu_if)); > + __vgic_v3_save_aprs(kern_hyp_va_host(cpu_if)); > } > > DEFINE_KVM_HOST_HCALL_VOID(__vgic_v3_restore_vmcr_aprs, 1, > - struct vgic_v3_cpu_if *, cpu_if) > + struct vgic_v3_cpu_if __hostva *, cpu_if) > { > - __vgic_v3_restore_vmcr_aprs(kern_hyp_va(cpu_if)); > + __vgic_v3_restore_vmcr_aprs(kern_hyp_va_host(cpu_if)); > } > > DEFINE_KVM_HOST_HCALL(int, __pkvm_init, 4, > @@ -579,16 +579,17 @@ DEFINE_KVM_HOST_HCALL_VOID(__pkvm_unreserve_vm, 1, > } > > DEFINE_KVM_HOST_HCALL(int, __pkvm_init_vm, 3, > - struct kvm *, host_kvm, void *, vm_hva, void *, pgd_hva) > + struct kvm __hostva *, host_kvm, void __hostva *, vm_hva, > + void __hostva *, pgd_hva) > { > - return __pkvm_init_vm(kern_hyp_va(host_kvm), vm_hva, pgd_hva); > + return __pkvm_init_vm(kern_hyp_va_host(host_kvm), vm_hva, pgd_hva); > } > > DEFINE_KVM_HOST_HCALL(int, __pkvm_init_vcpu, 3, > - pkvm_handle_t, handle, struct kvm_vcpu *, host_vcpu, > - void *, vcpu_hva) > + pkvm_handle_t, handle, struct kvm_vcpu __hostva *, host_vcpu, > + void __hostva *, vcpu_hva) > { > - return __pkvm_init_vcpu(handle, kern_hyp_va(host_vcpu), vcpu_hva); > + return __pkvm_init_vcpu(handle, kern_hyp_va_host(host_vcpu), vcpu_hva); > } > > DEFINE_KVM_HOST_HCALL0(int, __pkvm_vcpu_in_poison_fault) > @@ -623,7 +624,7 @@ DEFINE_KVM_HOST_HCALL(int, __pkvm_finalize_teardown_vm, 1, > } > > DEFINE_KVM_HOST_HCALL(int, __tracing_load, 2, > - void *, desc_hva, size_t, desc_size) > + void __hostva *, desc_hva, size_t, desc_size) > { > return __tracing_load(desc_hva, desc_size); > } > @@ -670,15 +671,15 @@ DEFINE_KVM_HOST_HCALL_VOID(__tracing_write_event, 1, > } > > DEFINE_KVM_HOST_HCALL_VOID(__vgic_v5_save_apr, 1, > - struct vgic_v5_cpu_if *, cpu_if) > + struct vgic_v5_cpu_if __hostva *, cpu_if) > { > - __vgic_v5_save_apr(kern_hyp_va(cpu_if)); > + __vgic_v5_save_apr(kern_hyp_va_host(cpu_if)); > } > > DEFINE_KVM_HOST_HCALL_VOID(__vgic_v5_restore_vmcr_apr, 1, > - struct vgic_v5_cpu_if *, cpu_if) > + struct vgic_v5_cpu_if __hostva *, cpu_if) > { > - __vgic_v5_restore_vmcr_apr(kern_hyp_va(cpu_if)); > + __vgic_v5_restore_vmcr_apr(kern_hyp_va_host(cpu_if)); > } > > typedef void (*hcall_t)(struct kvm_cpu_context *); > diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c > index 205c52535c887..bfc9f07f336a1 100644 > --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c > +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c > @@ -644,9 +644,9 @@ static size_t pkvm_get_hyp_vm_size(unsigned int nr_vcpus) > size_mul(sizeof(struct pkvm_hyp_vcpu *), nr_vcpus)); > } > > -static void *map_donated_memory_noclear(void *host_va, size_t size) > +static void *map_donated_memory_noclear(void __hostva *host_va, size_t size) > { > - void *va = kern_hyp_va(host_va); > + void *va = kern_hyp_va_host(host_va); > > if (!PAGE_ALIGNED(va)) > return NULL; > @@ -658,7 +658,7 @@ static void *map_donated_memory_noclear(void *host_va, size_t size) > return va; > } > > -static void *map_donated_memory(void *host_va, size_t size) > +static void *map_donated_memory(void __hostva *host_va, size_t size) > { > void *va = map_donated_memory_noclear(host_va, size); > > @@ -805,7 +805,8 @@ void teardown_selftest_vm(void) > * > * Return 0 success, negative error code on failure. > */ > -int __pkvm_init_vm(struct kvm *host_kvm, void *vm_hva, void *pgd_hva) > +int __pkvm_init_vm(struct kvm *host_kvm, void __hostva *vm_hva, > + void __hostva *pgd_hva) > { > struct pkvm_hyp_vm *hyp_vm = NULL; > size_t vm_size, pgd_size; > @@ -896,7 +897,7 @@ static int register_hyp_vcpu(struct pkvm_hyp_vm *hyp_vm, > } > > int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu, > - void *vcpu_hva) > + void __hostva *vcpu_hva) > { > struct pkvm_hyp_vcpu *hyp_vcpu; > struct pkvm_hyp_vm *hyp_vm; > diff --git a/arch/arm64/kvm/hyp/nvhe/trace.c b/arch/arm64/kvm/hyp/nvhe/trace.c > index 97203ddd3cf45..5d0fcdce9507d 100644 > --- a/arch/arm64/kvm/hyp/nvhe/trace.c > +++ b/arch/arm64/kvm/hyp/nvhe/trace.c > @@ -206,9 +206,9 @@ static bool hyp_trace_desc_is_valid(struct hyp_trace_desc *desc, size_t desc_siz > return true; > } > > -int __tracing_load(void *desc_hva, size_t desc_size) > +int __tracing_load(void __hostva *desc_hva, size_t desc_size) > { > - struct hyp_trace_desc *desc = kern_hyp_va(desc_hva); > + struct hyp_trace_desc *desc = kern_hyp_va_host(desc_hva); > int ret; > > ret = __admit_host_mem(desc, desc_size); > -- > 2.39.5 > -- Vincent