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envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Dec 12, 2025 at 11:10:23AM +0800, Xiaoyao Li wrote: > On 11/20/2025 1:29 AM, Peter Xu wrote: > > Detect supported guest-memfd flags by the current kernel, and reject > > creations of guest-memfd using invalid flags. When the cap isn't > > available, then no flag is supported. > > > > Signed-off-by: Peter Xu > > --- > > accel/kvm/kvm-all.c | 11 +++++++++++ > > 1 file changed, 11 insertions(+) > > > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > > index 96c194ce54..f477014126 100644 > > --- a/accel/kvm/kvm-all.c > > +++ b/accel/kvm/kvm-all.c > > @@ -108,6 +108,7 @@ static int kvm_sstep_flags; > > static bool kvm_immediate_exit; > > static uint64_t kvm_supported_memory_attributes; > > static bool kvm_guest_memfd_supported; > > +static uint64_t kvm_guest_memfd_flags_supported; > > static hwaddr kvm_max_slot_size = ~0; > > static const KVMCapabilityInfo kvm_required_capabilites[] = { > > @@ -2787,6 +2788,10 @@ static int kvm_init(AccelState *as, MachineState *ms) > > kvm_guest_memfd_supported = > > kvm_vm_check_extension(s, KVM_CAP_GUEST_MEMFD) && > > kvm_vm_check_extension(s, KVM_CAP_USER_MEMORY2); > > + > > + ret = kvm_vm_check_extension(s, KVM_CAP_GUEST_MEMFD_FLAGS); > > + kvm_guest_memfd_flags_supported = ret > 0 ? ret : 0; > > + > > kvm_pre_fault_memory_supported = kvm_vm_check_extension(s, KVM_CAP_PRE_FAULT_MEMORY); > > if (s->kernel_irqchip_split == ON_OFF_AUTO_AUTO) { > > @@ -4492,6 +4497,12 @@ int kvm_create_guest_memfd(uint64_t size, uint64_t flags, Error **errp) > > return -1; > > } > > + if (flags & ~kvm_guest_memfd_flags_supported) { > > + error_setg(errp, "KVM does not support guest-memfd flag: 0x%"PRIx64, > > I'm thinking if need to add "for current VM" like: > > KVM does not support guest-memfd flag: xxx for current VM > > because kvm_guest_memfd_flags_supported is got from VM-scope CAP and varies > for different VM types. Sure I can amend it. Though I plan to change the sentence slightly: if (flags & ~kvm_guest_memfd_flags_supported) { - error_setg(errp, "KVM does not support guest-memfd flag: 0x%"PRIx64, + error_setg(errp, "Current KVM instance does not support " + "guest-memfd flag: 0x%"PRIx64, flags & ~kvm_guest_memfd_flags_supported); return -1; } Thanks, > > > + flags & ~kvm_guest_memfd_flags_supported); > > + return -1; > > + } > > + > > fd = kvm_vm_ioctl(kvm_state, KVM_CREATE_GUEST_MEMFD, &guest_memfd); > > if (fd < 0) { > > error_setg_errno(errp, errno, "Error creating KVM guest_memfd"); > -- Peter Xu