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KVM: x86: Remove the KVM_GET_NR_MMU_PAGES ioctl 

The KVM_GET_NR_MMU_PAGES ioctl is quite questionable on 64-bit hosts
since it fails to return the full 64 bits of the value that can be
set with the corresponding KVM_SET_NR_MMU_PAGES call. Its "long" return
value is truncated into an "int" in the kvm_arch_vm_ioctl() function.

Since this ioctl also never has been used by userspace applications
(QEMU, Google's internal VMM, kvmtool and CrosVM have been checked),
it's likely the best if we remove this badly designed ioctl before
anybody really tries to use it.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230208140105.655814-4-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Thomas Huth 2023-02-08 15:01:02 +01:00 committed by Paolo Bonzini
parent 71fb165e23
commit c5edd753a0
3 changed files with 2 additions and 10 deletions
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8
arch/x86/kvm/x86.c
View File

@ -6021,11 +6021,6 @@ static int kvm_vm_ioctl_set_nr_mmu_pages(struct kvm *kvm,
return 0;
}
static unsigned long kvm_vm_ioctl_get_nr_mmu_pages(struct kvm *kvm)
{
return kvm->arch.n_max_mmu_pages;
}
static int kvm_vm_ioctl_get_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
{
struct kvm_pic *pic = kvm->arch.vpic;
@ -6711,9 +6706,6 @@ set_identity_unlock:
case KVM_SET_NR_MMU_PAGES:
r = kvm_vm_ioctl_set_nr_mmu_pages(kvm, arg);
break;
case KVM_GET_NR_MMU_PAGES:
r = kvm_vm_ioctl_get_nr_mmu_pages(kvm);
break;
case KVM_CREATE_IRQCHIP: {
mutex_lock(&kvm->lock);

2
include/uapi/linux/kvm.h
View File

@ -1451,7 +1451,7 @@ struct kvm_vfio_spapr_tce {
#define KVM_CREATE_VCPU _IO(KVMIO, 0x41)
#define KVM_GET_DIRTY_LOG _IOW(KVMIO, 0x42, struct kvm_dirty_log)
#define KVM_SET_NR_MMU_PAGES _IO(KVMIO, 0x44)
#define KVM_GET_NR_MMU_PAGES _IO(KVMIO, 0x45)
#define KVM_GET_NR_MMU_PAGES _IO(KVMIO, 0x45) /* deprecated */
#define KVM_SET_USER_MEMORY_REGION _IOW(KVMIO, 0x46, \
struct kvm_userspace_memory_region)
#define KVM_SET_TSS_ADDR _IO(KVMIO, 0x47)

2
tools/include/uapi/linux/kvm.h
View File

@ -1451,7 +1451,7 @@ struct kvm_vfio_spapr_tce {
#define KVM_CREATE_VCPU _IO(KVMIO, 0x41)
#define KVM_GET_DIRTY_LOG _IOW(KVMIO, 0x42, struct kvm_dirty_log)
#define KVM_SET_NR_MMU_PAGES _IO(KVMIO, 0x44)
#define KVM_GET_NR_MMU_PAGES _IO(KVMIO, 0x45)
#define KVM_GET_NR_MMU_PAGES _IO(KVMIO, 0x45) /* deprecated */
#define KVM_SET_USER_MEMORY_REGION _IOW(KVMIO, 0x46, \
struct kvm_userspace_memory_region)
#define KVM_SET_TSS_ADDR _IO(KVMIO, 0x47)