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>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ff7f398a0c6a98117cdf1578d2893c9265d0252e..4282daeaee847cc4b9c08d51261e7b1d1ed5151b 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -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);
 

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index d77aef872a0a07e767b2bddad095a250a9da1e65..4003a166328cc38027b4037527da91738944cf6b 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -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)

diff --git a/tools/include/uapi/linux/kvm.h b/tools/include/uapi/linux/kvm.h
index d77aef872a0a07e767b2bddad095a250a9da1e65..4003a166328cc38027b4037527da91738944cf6b 100644 (file)
--- a/tools/include/uapi/linux/kvm.h
+++ b/tools/include/uapi/linux/kvm.h
@@ -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)