On Mon, Mar 28, 2022 at 10:33:37PM +0000, Sean Christopherson wrote: > On Thu, Mar 10, 2022, Chao Peng wrote: > > 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. > > > > After private memory is enabled, this new exit will be used for KVM to > > exit to userspace for shared memory <-> 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 > > do the map/unmap operations. > > - implicit conversion: happens in KVM page fault handler. > > * if the fault is due to a private memory access then causes a > > userspace exit for a shared->private conversion request when the > > page has not been allocated in the private memory backend. > > * If the fault is due to a shared memory access then causes a > > userspace exit for a private->shared conversion request when the > > page has already been allocated in the private memory backend. > > > > Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx> > > Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx> > > --- > > Documentation/virt/kvm/api.rst | 22 ++++++++++++++++++++++ > > include/uapi/linux/kvm.h | 9 +++++++++ > > 2 files changed, 31 insertions(+) > > > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > index f76ac598606c..bad550c2212b 100644 > > --- a/Documentation/virt/kvm/api.rst > > +++ b/Documentation/virt/kvm/api.rst > > @@ -6216,6 +6216,28 @@ 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_ERROR */ > > + struct { > > + #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1 << 0) > > + __u32 flags; > > + __u32 padding; > > + __u64 gpa; > > + __u64 size; > > + } memory; > > +If exit reason is KVM_EXIT_MEMORY_ERROR then it indicates that the VCPU has > > Doh, I'm pretty sure I suggested KVM_EXIT_MEMORY_ERROR. Any objection to using > KVM_EXIT_MEMORY_FAULT instead of KVM_EXIT_MEMORY_ERROR? "ERROR" makes me think > of ECC errors, i.e. uncorrected #MC in x86 land, not more generic "faults". That > would align nicely with -EFAULT. Sure. > > > +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.
