Re: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory
From: Sean Christopherson <seanjc@google.com>
Date: 2023-07-20 15:15:39
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kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-fsdevel, linux-mips, linux-mm, linux-riscv, linuxppc-dev, lkml
On Thu, Jul 20, 2023, Xiaoyao Li wrote:
On 7/19/2023 7:44 AM, Sean Christopherson wrote:quoted
@@ -5134,6 +5167,16 @@ static long kvm_vm_ioctl(struct file *filp, case KVM_GET_STATS_FD: r = kvm_vm_ioctl_get_stats_fd(kvm); break; + case KVM_CREATE_GUEST_MEMFD: { + struct kvm_create_guest_memfd guest_memfd; + + r = -EFAULT; + if (copy_from_user(&guest_memfd, argp, sizeof(guest_memfd))) + goto out; + + r = kvm_gmem_create(kvm, &guest_memfd); + break; + }Does it need a new CAP to indicate the support of guest_memfd?
Yeah, I meant to add that to the TODO list and forgot (obviously).
This is patch series introduces 3 new CAPs and it seems any one of them can serve as the indicator of guest_memfd. +#define KVM_CAP_USER_MEMORY2 230 +#define KVM_CAP_MEMORY_ATTRIBUTES 231 +#define KVM_CAP_VM_TYPES 232
The number of new caps being added is the main why I didn't just add another one. On the other hand, we have room for a few billion caps, so one more isn't a big deal. So yeah, KVM_CAP_GUEST_MEMFD is probably the way to go.