| Message ID | 20230718234512.1690985-8-seanjc@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | KVM: guest_memfd() and per-page attributes | expand |
On Tue, Jul 18, 2023 at 04:44:50PM -0700, Sean Christopherson wrote: > From: Chao Peng <chao.p.peng@linux.intel.com> > > This new KVM exit allows userspace to handle memory-related errors. It > indicates an error happens in KVM at guest memory range [gpa, gpa+size). > The flags includes additional information for userspace to handle the > error. Currently bit 0 is defined as 'private memory' where '1' > indicates error happens due to private memory access and '0' indicates > error happens due to shared memory access. Now it's bit 3: #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1ULL << 3) I remember some other attributes were introduced in v10 yet: #define KVM_MEMORY_ATTRIBUTE_READ (1ULL << 0) #define KVM_MEMORY_ATTRIBUTE_WRITE (1ULL << 1) #define KVM_MEMORY_ATTRIBUTE_EXECUTE (1ULL << 2) #define KVM_MEMORY_ATTRIBUTE_PRIVATE (1ULL << 3) So KVM_MEMORY_EXIT_FLAG_PRIVATE changed to bit 3 due to above things, or other reason ? (Sorry I didn't follow v10 too much before). > > When private memory is enabled, this new exit will be used for KVM to > exit to userspace for shared <-> private memory conversion in memory > encryption usage. In such usage, typically there are two kind of memory > conversions: > - explicit conversion: happens when guest explicitly calls into KVM > to map a range (as private or shared), KVM then exits to userspace > to perform the map/unmap operations. > - implicit conversion: happens in KVM page fault handler where KVM > exits to userspace for an implicit conversion when the page is in a > different state than requested (private or shared). > > Suggested-by: Sean Christopherson <seanjc@google.com> > Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com> > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com> > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> > Reviewed-by: Fuad Tabba <tabba@google.com> > Tested-by: Fuad Tabba <tabba@google.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > Documentation/virt/kvm/api.rst | 22 ++++++++++++++++++++++ > include/uapi/linux/kvm.h | 8 ++++++++ > 2 files changed, 30 insertions(+) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index c0ddd3035462..34d4ce66e0c8 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -6700,6 +6700,28 @@ array field represents return values. The userspace should update the return > values of SBI call before resuming the VCPU. For more details on RISC-V SBI > spec refer, https://github.com/riscv/riscv-sbi-doc. > > +:: > + > + /* KVM_EXIT_MEMORY_FAULT */ > + struct { > + #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1ULL << 3) > + __u64 flags; > + __u64 gpa; > + __u64 size; > + } memory; > + > +If exit reason is KVM_EXIT_MEMORY_FAULT then it indicates that the VCPU has > +encountered a memory error which is not handled by KVM kernel module and > +userspace may choose to handle it. The 'flags' field indicates the memory > +properties of the exit. > + > + - KVM_MEMORY_EXIT_FLAG_PRIVATE - indicates the memory error is caused by > + private memory access when the bit is set. Otherwise the memory error is > + caused by shared memory access when the bit is clear. > + > +'gpa' and 'size' indicate the memory range the error occurs at. The userspace > +may handle the error and return to KVM to retry the previous memory access. > + > :: > > /* KVM_EXIT_NOTIFY */ > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 4d4b3de8ac55..6c6ed214b6ac 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -274,6 +274,7 @@ struct kvm_xen_exit { > #define KVM_EXIT_RISCV_SBI 35 > #define KVM_EXIT_RISCV_CSR 36 > #define KVM_EXIT_NOTIFY 37 > +#define KVM_EXIT_MEMORY_FAULT 38 > > /* For KVM_EXIT_INTERNAL_ERROR */ > /* Emulate instruction failed. */ > @@ -520,6 +521,13 @@ struct kvm_run { > #define KVM_NOTIFY_CONTEXT_INVALID (1 << 0) > __u32 flags; > } notify; > + /* KVM_EXIT_MEMORY_FAULT */ > + struct { > +#define KVM_MEMORY_EXIT_FLAG_PRIVATE (1ULL << 3) > + __u64 flags; > + __u64 gpa; > + __u64 size; > + } memory; > /* Fix the size of the union. */ > char padding[256]; > }; > -- > 2.41.0.255.g8b1d071c50-goog >
On Wed, Jul 19, 2023, Yuan Yao wrote: > On Tue, Jul 18, 2023 at 04:44:50PM -0700, Sean Christopherson wrote: > > From: Chao Peng <chao.p.peng@linux.intel.com> > > > > This new KVM exit allows userspace to handle memory-related errors. It > > indicates an error happens in KVM at guest memory range [gpa, gpa+size). > > The flags includes additional information for userspace to handle the > > error. Currently bit 0 is defined as 'private memory' where '1' > > indicates error happens due to private memory access and '0' indicates > > error happens due to shared memory access. > > Now it's bit 3: Yeah, I need to update (or write) a lot of changelogs. > #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1ULL << 3) > > I remember some other attributes were introduced in v10 yet: > > #define KVM_MEMORY_ATTRIBUTE_READ (1ULL << 0) > #define KVM_MEMORY_ATTRIBUTE_WRITE (1ULL << 1) > #define KVM_MEMORY_ATTRIBUTE_EXECUTE (1ULL << 2) > #define KVM_MEMORY_ATTRIBUTE_PRIVATE (1ULL << 3) > > So KVM_MEMORY_EXIT_FLAG_PRIVATE changed to bit 3 due to above things, > or other reason ? (Sorry I didn't follow v10 too much before). Yep, I want to reserve space for the RWX bits.
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index c0ddd3035462..34d4ce66e0c8 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6700,6 +6700,28 @@ array field represents return values. The userspace should update the return values of SBI call before resuming the VCPU. For more details on RISC-V SBI spec refer, https://github.com/riscv/riscv-sbi-doc. +:: + + /* KVM_EXIT_MEMORY_FAULT */ + struct { + #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1ULL << 3) + __u64 flags; + __u64 gpa; + __u64 size; + } memory; + +If exit reason is KVM_EXIT_MEMORY_FAULT then it indicates that the VCPU has +encountered a memory error which is not handled by KVM kernel module and +userspace may choose to handle it. The 'flags' field indicates the memory +properties of the exit. + + - KVM_MEMORY_EXIT_FLAG_PRIVATE - indicates the memory error is caused by + private memory access when the bit is set. Otherwise the memory error is + caused by shared memory access when the bit is clear. + +'gpa' and 'size' indicate the memory range the error occurs at. The userspace +may handle the error and return to KVM to retry the previous memory access. + :: /* KVM_EXIT_NOTIFY */ diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 4d4b3de8ac55..6c6ed214b6ac 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -274,6 +274,7 @@ struct kvm_xen_exit { #define KVM_EXIT_RISCV_SBI 35 #define KVM_EXIT_RISCV_CSR 36 #define KVM_EXIT_NOTIFY 37 +#define KVM_EXIT_MEMORY_FAULT 38 /* For KVM_EXIT_INTERNAL_ERROR */ /* Emulate instruction failed. */ @@ -520,6 +521,13 @@ struct kvm_run { #define KVM_NOTIFY_CONTEXT_INVALID (1 << 0) __u32 flags; } notify; + /* KVM_EXIT_MEMORY_FAULT */ + struct { +#define KVM_MEMORY_EXIT_FLAG_PRIVATE (1ULL << 3) + __u64 flags; + __u64 gpa; + __u64 size; + } memory; /* Fix the size of the union. */ char padding[256]; };