KVM: MMU: Discard reserved bits checking on PDE bit 7-8
1. It's related to a Linux kernel bug which fixed by Ingo on
07a66d7c53a538e1a9759954a82bb6c07365eff9. The original code exists for quite a
long time, and it would convert a PDE for large page into a normal PDE. But it
fail to fit normal PDE well. With the code before Ingo's fix, the kernel would
fall reserved bit checking with bit 8 - the remaining global bit of PTE. So the
kernel would receive a double-fault.
2. After discussion, we decide to discard PDE bit 7-8 reserved checking for now.
For this marked as reserved in SDM, but didn't checked by the processor in
fact...
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index da3ad3c..b582add 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2194,7 +2194,7 @@
rsvd_bits(maxphyaddr, 63) |
rsvd_bits(7, 8) | rsvd_bits(1, 2); /* PDPTE */
context->rsvd_bits_mask[0][1] = exb_bit_rsvd |
- rsvd_bits(maxphyaddr, 62); /* PDE */
+ rsvd_bits(maxphyaddr, 62); /* PDE */
context->rsvd_bits_mask[0][0] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 62); /* PTE */
context->rsvd_bits_mask[1][1] = exb_bit_rsvd |
@@ -2208,13 +2208,14 @@
context->rsvd_bits_mask[0][2] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 51) | rsvd_bits(7, 8);
context->rsvd_bits_mask[0][1] = exb_bit_rsvd |
- rsvd_bits(maxphyaddr, 51) | rsvd_bits(7, 8);
+ rsvd_bits(maxphyaddr, 51);
context->rsvd_bits_mask[0][0] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 51);
context->rsvd_bits_mask[1][3] = context->rsvd_bits_mask[0][3];
context->rsvd_bits_mask[1][2] = context->rsvd_bits_mask[0][2];
context->rsvd_bits_mask[1][1] = exb_bit_rsvd |
- rsvd_bits(maxphyaddr, 51) | rsvd_bits(13, 20);
+ rsvd_bits(maxphyaddr, 51) |
+ rsvd_bits(13, 20); /* large page */
context->rsvd_bits_mask[1][0] = ~0ull;
break;
}
