On 18.11.21 00:44, Sean Christopherson wrote:

On Tue, Nov 16, 2021, Juergen Gross wrote:

quoted

diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index 816a82515dcd..64ba9b1c8b3d 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c

@@ -685,11 +685,21 @@ static const struct kvm_io_device_ops ioapic_mmio_ops = {
  int kvm_ioapic_init(struct kvm *kvm)
  {
  	struct kvm_ioapic *ioapic;
+	size_t sz;
  	int ret;
  
-	ioapic = kzalloc(sizeof(struct kvm_ioapic), GFP_KERNEL_ACCOUNT);
+	sz = sizeof(struct kvm_ioapic) +
+	     sizeof(*ioapic->rtc_status.dest_map.map) *
+		    BITS_TO_LONGS(KVM_MAX_VCPU_IDS) +
+	     sizeof(*ioapic->rtc_status.dest_map.vectors) *
+		    (KVM_MAX_VCPU_IDS);
+	ioapic = kzalloc(sz, GFP_KERNEL_ACCOUNT);
  	if (!ioapic)
  		return -ENOMEM;
+	ioapic->rtc_status.dest_map.map = (void *)(ioapic + 1);

Oof.  Just do separate allocations.  I highly doubt the performance of the
emulated RTC hinges on the spatial locality of the bitmap and array.  The array
is going to end up in a second page for most configuration anyways.

Okay, fine with me.


Juergen