tree 70514ff9adf2b8d2d865b71a50cef2b6f1e670e7
parent b07ffc349e797217410a7fef44fbc32e584be481
author Krish Sadhukhan <krish.sadhukhan@oracle.com> 1602011213 +0000
committer Paolo Bonzini <pbonzini@redhat.com> 1603123591 -0400

nSVM: Test non-MBZ reserved bits in CR3 in long mode and legacy PAE mode

According to section "CR3" in APM vol. 2, the non-MBZ reserved bits in CR3
need to be set by software as follows:

	"Reserved Bits. Reserved fields should be cleared to 0 by software
	when writing CR3."

But experiments show that consistency checking in SVM ignores these
non-MBZ-reserved bits in CR3, meaning they can be set to 1 also. However,
setting them to 1 may cause guest crashes in some modes and in bare metal
environments. Hence, this test induces an #NPF by clearing the "P" bit in
the highest level page table, when testing the 1-setting of these bits.
Inducing an #NPF causes the guest to exit to userspace before any guest
instruction is executed thus avoiding any crash.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Message-Id: <20201006190654.32305-4-krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>