On Wed, Jul 28, 2021 at 10:52:16AM -0400, Tianyu Lan wrote:
> +static int hyperv_init_ghcb(void)
> +{
> + u64 ghcb_gpa;
> + void *ghcb_va;
> + void **ghcb_base;
> +
> + if (!ms_hyperv.ghcb_base)
> + return -EINVAL;
> +
> + rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
> + ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB);
This deserves a comment. As I understand it, the GHCB pa is set by
Hyper-V or the paravisor, so the page does not need to be allocated by
Linux.
And it is not mapped unencrypted because the GHCB page is allocated
above the VTOM boundary?
> @@ -167,6 +190,31 @@ static int hv_cpu_die(unsigned int cpu)
> {
> struct hv_reenlightenment_control re_ctrl;
> unsigned int new_cpu;
> + unsigned long flags;
> + void **input_arg;
> + void *pg;
> + void **ghcb_va = NULL;
> +
> + local_irq_save(flags);
> + input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
> + pg = *input_arg;
Pg is never used later on, why is it set?
