| Message ID | 20211201170411.1561936-16-qperret@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: Introduce kvm_share_hyp() | expand |
On Wed, Dec 01, 2021 at 05:04:09PM +0000, Quentin Perret wrote: > Make use of the newly introduced unshare hypercall during guest teardown > to unmap guest-related data structures from the hyp stage-1. > > Signed-off-by: Quentin Perret <qperret@google.com> > --- > arch/arm64/include/asm/kvm_host.h | 2 ++ > arch/arm64/include/asm/kvm_mmu.h | 1 + > arch/arm64/kvm/arm.c | 2 ++ > arch/arm64/kvm/fpsimd.c | 34 ++++++++++++++++++++++--- > arch/arm64/kvm/mmu.c | 42 +++++++++++++++++++++++++++++++ > arch/arm64/kvm/reset.c | 8 +++++- > 6 files changed, 85 insertions(+), 4 deletions(-) [...] > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index d72566896755..8e506ba8988e 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -344,6 +344,32 @@ static int share_pfn_hyp(u64 pfn) > return ret; > } > > +static int unshare_pfn_hyp(u64 pfn) > +{ > + struct rb_node **node, *parent; > + struct hyp_shared_pfn *this; > + int ret = 0; > + > + mutex_lock(&hyp_shared_pfns_lock); > + this = find_shared_pfn(pfn, &node, &parent); > + if (WARN_ON(!this)) { > + ret = -EINVAL; -ENOENT? > + goto unlock; > + } > + > + this->count--; > + if (this->count) > + goto unlock; Again, if we did an RCU lookup then this could be converted to a refcount_t to take the mutex only when it hits zero. But for now I think it's fine. > + > + rb_erase(&this->node, &hyp_shared_pfns); > + kfree(this); > + ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn, 1); > +unlock: > + mutex_unlock(&hyp_shared_pfns_lock); > + > + return ret; > +} > + > int kvm_share_hyp(void *from, void *to) > { > phys_addr_t start, end, cur; > @@ -376,6 +402,22 @@ int kvm_share_hyp(void *from, void *to) > return 0; > } > > +void kvm_unshare_hyp(void *from, void *to) > +{ > + phys_addr_t start, end, cur; > + u64 pfn; > + > + if (is_kernel_in_hyp_mode() || kvm_host_owns_hyp_mappings() || !from) I don't think you need the is_kernel_in_hyp_mode() check any more not that you've moved that into kvm_host_owns_hyp_mappings(). Will
On Thursday 09 Dec 2021 at 11:22:33 (+0000), Will Deacon wrote: > On Wed, Dec 01, 2021 at 05:04:09PM +0000, Quentin Perret wrote: > > Make use of the newly introduced unshare hypercall during guest teardown > > to unmap guest-related data structures from the hyp stage-1. > > > > Signed-off-by: Quentin Perret <qperret@google.com> > > --- > > arch/arm64/include/asm/kvm_host.h | 2 ++ > > arch/arm64/include/asm/kvm_mmu.h | 1 + > > arch/arm64/kvm/arm.c | 2 ++ > > arch/arm64/kvm/fpsimd.c | 34 ++++++++++++++++++++++--- > > arch/arm64/kvm/mmu.c | 42 +++++++++++++++++++++++++++++++ > > arch/arm64/kvm/reset.c | 8 +++++- > > 6 files changed, 85 insertions(+), 4 deletions(-) > > [...] > > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > > index d72566896755..8e506ba8988e 100644 > > --- a/arch/arm64/kvm/mmu.c > > +++ b/arch/arm64/kvm/mmu.c > > @@ -344,6 +344,32 @@ static int share_pfn_hyp(u64 pfn) > > return ret; > > } > > > > +static int unshare_pfn_hyp(u64 pfn) > > +{ > > + struct rb_node **node, *parent; > > + struct hyp_shared_pfn *this; > > + int ret = 0; > > + > > + mutex_lock(&hyp_shared_pfns_lock); > > + this = find_shared_pfn(pfn, &node, &parent); > > + if (WARN_ON(!this)) { > > + ret = -EINVAL; > > -ENOENT? Sure. > > + goto unlock; > > + } > > + > > + this->count--; > > + if (this->count) > > + goto unlock; > > Again, if we did an RCU lookup then this could be converted to a refcount_t > to take the mutex only when it hits zero. But for now I think it's fine. No objection to do this in the future, but yeah I think we might as well start simple :) > > + > > + rb_erase(&this->node, &hyp_shared_pfns); > > + kfree(this); > > + ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn, 1); > > +unlock: > > + mutex_unlock(&hyp_shared_pfns_lock); > > + > > + return ret; > > +} > > + > > int kvm_share_hyp(void *from, void *to) > > { > > phys_addr_t start, end, cur; > > @@ -376,6 +402,22 @@ int kvm_share_hyp(void *from, void *to) > > return 0; > > } > > > > +void kvm_unshare_hyp(void *from, void *to) > > +{ > > + phys_addr_t start, end, cur; > > + u64 pfn; > > + > > + if (is_kernel_in_hyp_mode() || kvm_host_owns_hyp_mappings() || !from) > > I don't think you need the is_kernel_in_hyp_mode() check any more not that > you've moved that into kvm_host_owns_hyp_mappings(). The logic is a little odd, but I think I still do as kvm_host_owns_hyp_mappings() will return false if is_kernel_in_hyp_mode() is true.
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index cf858a7e3533..9360a2804df1 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -321,6 +321,7 @@ struct kvm_vcpu_arch { struct kvm_guest_debug_arch external_debug_state; struct user_fpsimd_state *host_fpsimd_state; /* hyp VA */ + struct task_struct *parent_task; struct { /* {Break,watch}point registers */ @@ -737,6 +738,7 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu); +void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu); static inline bool kvm_pmu_counter_deferred(struct perf_event_attr *attr) { diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 185d0f62b724..81839e9a8a24 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -151,6 +151,7 @@ static __always_inline unsigned long __kern_hyp_va(unsigned long v) #include <asm/stage2_pgtable.h> int kvm_share_hyp(void *from, void *to); +void kvm_unshare_hyp(void *from, void *to); int create_hyp_mappings(void *from, void *to, enum kvm_pgtable_prot prot); int create_hyp_io_mappings(phys_addr_t phys_addr, size_t size, void __iomem **kaddr, diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index c202abb448b1..6057f3c5aafe 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -188,6 +188,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm) } } atomic_set(&kvm->online_vcpus, 0); + + kvm_unshare_hyp(kvm, kvm + 1); } int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 86899d3aa9a9..2f48fd362a8c 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -14,6 +14,19 @@ #include <asm/kvm_mmu.h> #include <asm/sysreg.h> +void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu) +{ + struct task_struct *p = vcpu->arch.parent_task; + struct user_fpsimd_state *fpsimd; + + if (!is_protected_kvm_enabled() || !p) + return; + + fpsimd = &p->thread.uw.fpsimd_state; + kvm_unshare_hyp(fpsimd, fpsimd + 1); + put_task_struct(p); +} + /* * Called on entry to KVM_RUN unless this vcpu previously ran at least * once and the most recent prior KVM_RUN for this vcpu was called from @@ -29,12 +42,27 @@ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu) struct user_fpsimd_state *fpsimd = ¤t->thread.uw.fpsimd_state; + kvm_vcpu_unshare_task_fp(vcpu); + /* Make sure the host task fpsimd state is visible to hyp: */ ret = kvm_share_hyp(fpsimd, fpsimd + 1); - if (!ret) - vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd); + if (ret) + return ret; + + vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd); + + /* + * We need to keep current's task_struct pinned until its data has been + * unshared with the hypervisor to make sure it is not re-used by the + * kernel and donated to someone else while already shared -- see + * kvm_vcpu_unshare_task_fp() for the matching put_task_struct(). + */ + if (is_protected_kvm_enabled()) { + get_task_struct(current); + vcpu->arch.parent_task = current; + } - return ret; + return 0; } /* diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index d72566896755..8e506ba8988e 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -344,6 +344,32 @@ static int share_pfn_hyp(u64 pfn) return ret; } +static int unshare_pfn_hyp(u64 pfn) +{ + struct rb_node **node, *parent; + struct hyp_shared_pfn *this; + int ret = 0; + + mutex_lock(&hyp_shared_pfns_lock); + this = find_shared_pfn(pfn, &node, &parent); + if (WARN_ON(!this)) { + ret = -EINVAL; + goto unlock; + } + + this->count--; + if (this->count) + goto unlock; + + rb_erase(&this->node, &hyp_shared_pfns); + kfree(this); + ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn, 1); +unlock: + mutex_unlock(&hyp_shared_pfns_lock); + + return ret; +} + int kvm_share_hyp(void *from, void *to) { phys_addr_t start, end, cur; @@ -376,6 +402,22 @@ int kvm_share_hyp(void *from, void *to) return 0; } +void kvm_unshare_hyp(void *from, void *to) +{ + phys_addr_t start, end, cur; + u64 pfn; + + if (is_kernel_in_hyp_mode() || kvm_host_owns_hyp_mappings() || !from) + return; + + start = ALIGN_DOWN(__pa(from), PAGE_SIZE); + end = PAGE_ALIGN(__pa(to)); + for (cur = start; cur < end; cur += PAGE_SIZE) { + pfn = __phys_to_pfn(cur); + WARN_ON(unshare_pfn_hyp(pfn)); + } +} + /** * create_hyp_mappings - duplicate a kernel virtual address range in Hyp mode * @from: The virtual kernel start address of the range diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index e3e2a79fbd75..798a84eddbde 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -150,7 +150,13 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu) void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu) { - kfree(vcpu->arch.sve_state); + void *sve_state = vcpu->arch.sve_state; + + kvm_vcpu_unshare_task_fp(vcpu); + kvm_unshare_hyp(vcpu, vcpu + 1); + if (sve_state) + kvm_unshare_hyp(sve_state, sve_state + vcpu_sve_state_size(vcpu)); + kfree(sve_state); } static void kvm_vcpu_reset_sve(struct kvm_vcpu *vcpu)
Make use of the newly introduced unshare hypercall during guest teardown to unmap guest-related data structures from the hyp stage-1. Signed-off-by: Quentin Perret <qperret@google.com> --- arch/arm64/include/asm/kvm_host.h | 2 ++ arch/arm64/include/asm/kvm_mmu.h | 1 + arch/arm64/kvm/arm.c | 2 ++ arch/arm64/kvm/fpsimd.c | 34 ++++++++++++++++++++++--- arch/arm64/kvm/mmu.c | 42 +++++++++++++++++++++++++++++++ arch/arm64/kvm/reset.c | 8 +++++- 6 files changed, 85 insertions(+), 4 deletions(-)