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Krish Sadhukhan authored
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>
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