Messages in this thread | | | Subject | Re: [RFC PATCH 5/6] kvm: x86: add KVM_EXIT_MEMORY_ERROR exit | From | Mika Penttilä <> | Date | Thu, 11 Nov 2021 17:08:47 +0200 |
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On 11.11.2021 16.13, Chao Peng wrote: > Currently support to exit to userspace for private/shared memory > conversion. > > Signed-off-by: Sean Christopherson <seanjc@google.com> > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com> > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> > --- > arch/x86/kvm/mmu/mmu.c | 20 ++++++++++++++++++++ > include/uapi/linux/kvm.h | 15 +++++++++++++++ > 2 files changed, 35 insertions(+) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index af5ecf4ef62a..780868888aa8 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -3950,6 +3950,17 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, > > slot = __kvm_vcpu_gfn_to_memslot(vcpu, gfn, private); > > + /* > + * Exit to userspace to map the requested private/shared memory region > + * if there is no memslot and (a) the access is private or (b) there is > + * an existing private memslot. Emulated MMIO must be accessed through > + * shared GPAs, thus a memslot miss on a private GPA is always handled > + * as an implicit conversion "request". > + */ > + if (!slot && > + (private || __kvm_vcpu_gfn_to_memslot(vcpu, gfn, true))) > + goto out_convert; > + > /* Don't expose aliases for no slot GFNs or private memslots */ > if ((cr2_or_gpa & vcpu_gpa_stolen_mask(vcpu)) && > !kvm_is_visible_memslot(slot)) { > @@ -3994,6 +4005,15 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, > *pfn = __gfn_to_pfn_memslot(slot, gfn, false, NULL, > write, writable, hva); > return false; > + > +out_convert: > + vcpu->run->exit_reason = KVM_EXIT_MEMORY_ERROR; > + vcpu->run->mem.type = private ? KVM_EXIT_MEM_MAP_PRIVATE > + : KVM_EXIT_MEM_MAP_SHARE; > + vcpu->run->mem.u.map.gpa = cr2_or_gpa; > + vcpu->run->mem.u.map.size = PAGE_SIZE; > + return true; > + > I think this does just retry, no exit to user space?
> } > > static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 8d20caae9180..470c472a9451 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -233,6 +233,18 @@ struct kvm_xen_exit { > } u; > }; > > +struct kvm_memory_exit { > +#define KVM_EXIT_MEM_MAP_SHARE 1 > +#define KVM_EXIT_MEM_MAP_PRIVATE 2 > + __u32 type; > + union { > + struct { > + __u64 gpa; > + __u64 size; > + } map; > + } u; > +}; > + > #define KVM_S390_GET_SKEYS_NONE 1 > #define KVM_S390_SKEYS_MAX 1048576 > > @@ -272,6 +284,7 @@ struct kvm_xen_exit { > #define KVM_EXIT_X86_BUS_LOCK 33 > #define KVM_EXIT_XEN 34 > #define KVM_EXIT_TDVMCALL 35 > +#define KVM_EXIT_MEMORY_ERROR 36 > > /* For KVM_EXIT_INTERNAL_ERROR */ > /* Emulate instruction failed. */ > @@ -455,6 +468,8 @@ struct kvm_run { > __u64 subfunc; > __u64 param[4]; > } tdvmcall; > + /* KVM_EXIT_MEMORY_ERROR */ > + struct kvm_memory_exit mem; > /* Fix the size of the union. */ > char padding[256]; > };
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