Commit 6d0ecbf6 authored by Krish Sadhukhan's avatar Krish Sadhukhan Committed by Paolo Bonzini

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: default avatarKrish Sadhukhan <krish.sadhukhan@oracle.com>
Message-Id: <20201006190654.32305-4-krish.sadhukhan@oracle.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b07ffc34
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