Add Virtualization Exception handler #629
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TDG.VP.VMCALL<Instruction.CPUID> is used to request the VMM to emulate CPUID operations. Signed-off-by: Peter Fang <peter.fang@intel.com>
TDG.VP.VEINFO.GET is used to get Virtualization Exception Information for the recent #VE exception. Signed-off-by: Peter Fang <peter.fang@intel.com>
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LGTM, thanks @peterfang. I will also request a review from @msft-jlange and merge upon his approval.
kernel/src/cpu/ve.rs
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| let veinfo = tdcall_get_ve_info().expect("Failed to get #VE info"); | ||
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| match veinfo.exit_reason { | ||
| VMX_EXIT_REASON_CPUID => handle_cpuid(ctx), |
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I'd like to consider adding IO emulation in the near future because that should be low-hanging fruit. There is much that can be copied from the instruction emulator and/or the #VC handler.
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I can add IO emulation after this PR. While we're on this subject, how do you feel about possibly replacing our current instruction decoder with a public crate such as zydis? I just checked and it supports no_std + decoder-only compilation.
The reason for this is because x86 instruction decoding is notoriously difficult to get right and bugs in this area tend to be quite challenging to triage. The decoder we previously upstreamed was an in-house development and not fully stress-tested or fuzzed. We could also continue to improve our coconut fuzzer but I'm open to exploring whether we could just delegate that to a well-known decoder. This of course would take time and would not be done right away.
Intel TD can receive #VE in certain cases and it should be handled by SVSM. Introduce a virtualization exception handler to handle them. Only the CPUID exit reason is handled right now. Co-developed-by: Peter Fang <peter.fang@intel.com> Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Intel TD can receive #VE in certain cases and it should be handled by SVSM. Introduce a virtualization exception handler to handle them. Only the CPUID exit reason is handled right now.