>Regarding question #3 from the cover letter:
>
> 3. Two helpers, cpu_vmcs_load() and cpu_vmcs_store(), are added in patch 3
> to save and restore the current VMCS. KVM has a variant of cpu_vmcs_load(),
> i.e., vmcs_load(). Extracting KVM's version would cause a lot of code
> churn, and I don't think that can be justified for reducing ~16 LoC
> duplication. Please let me know if you disagree.
>
>I'm fine with the SEAMLDR code having its own code, because I agree it's not worth
>extracting KVM's macro maze just to get at VMPTRLD. But I'm not fine with creating
>a new, inferior framework. So if we elect to leave KVM alone for the time being,
>I would prefer to simply open code VMPTRST and VMPTRLD in seamldr.c, e.g.
Agreed. And the code below makes perfect sense to me, so I will incorporate it
into my next version.
Thanks for your prompt feedback.
>
>static inline int seamldr_call(u64 fn, struct tdx_module_args *args)
>{
> u64 vmcs;
> int ret;
>
> if (!is_seamldr_call(fn))
> return -EINVAL;
>
> /*
> * SEAMRET from P-SEAMLDR invalidates the current VMCS. Save/restore
> * the VMCS across P-SEAMLDR SEAMCALLs to avoid clobbering KVM state.
> * Disable interrupts as KVM is allowed to do VMREAD/VMWRITE in IRQ
> * context (but not NMI context).
> */
> guard(irqsave)();
>
> asm goto("1: vmptrst %0\n\t"
> _ASM_EXTABLE(1b, %l[error])
> : "=m" (&vmcs) : "cc" : error);
>
> ret = seamldr_prerr(fn, args);
>
> /*
> * Restore the current VMCS pointer. VMPTSTR "returns" all ones if the
> * current VMCS is invalid.
> */
> if (vmcs != -1ULL) {
> asm goto("1: vmptrld %0\n\t"
> "jna %l[error]\n\t"
> _ASM_EXTABLE(1b, %l[error])
> : : "m" (&vmcs) : "cc" : error);
> }
>
> return ret;
>
>error:
> WARN_ONCE(1, "Failed to save/restore the current VMCS");
> return -EIO;
>}
