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 <[email protected]> --- arch/x86/kvm/mmu.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index e0f63b6..a0b130d 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2196,7 +2196,7 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu, int level) break; case PT32E_ROOT_LEVEL: 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 | @@ -2210,13 +2210,14 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu, int level) 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; } -- 1.5.4.5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
