virtualization

Difference between Sensitive Instructions and Privileged Instructions

徘徊边缘 提交于 2020-08-06 04:34:51
问题 I've been searching for a clear difference b/w a Sensitive and Privileged instruction but its all blurry right now. As far as i know: A sensitive instruction NEEDS TO trap to kernel mode if executed in User space else it gets ignored while a Privileged instruction WILL TRAP to Kernel mode if executed in User space. This difference is vague and unsatisfactory for me. Feel free to drop an AWESOME answer! EDIT: Just a thought, are these the same thing? 回答1: The terms are usually used in the

Do x86 instructions require their own encoding as well as all of their arguments to be present in memory at the same time?

妖精的绣舞 提交于 2020-07-27 09:26:37
问题 I am trying to figure out whether it is possible to run a Linux VM whose RAM is only backed by a single physical page. To simulate this, I modified the nested page fault handler in KVM to remove the present bit from all nested page table (NPT) entries, except the one corresponding to the currently processed page fault. While trying to start a Linux guest, I observed that assembly instructions that use memory operands, like add [rbp+0x820DDA], ebp lead to a page fault loop until I restore the

Do x86 instructions require their own encoding as well as all of their arguments to be present in memory at the same time?

丶灬走出姿态 提交于 2020-07-27 09:26:27
问题 I am trying to figure out whether it is possible to run a Linux VM whose RAM is only backed by a single physical page. To simulate this, I modified the nested page fault handler in KVM to remove the present bit from all nested page table (NPT) entries, except the one corresponding to the currently processed page fault. While trying to start a Linux guest, I observed that assembly instructions that use memory operands, like add [rbp+0x820DDA], ebp lead to a page fault loop until I restore the