Re: [PATCH 01/13] x86/HV: Initialize GHCB page in Isolation VM
From: Joerg Roedel <joro@8bytes.org>
Date: 2021-08-02 11:53:38
Also in:
linux-hyperv, linux-iommu, linux-scsi, lkml, netdev, xen-devel
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?
quoted hunk ↗ jump to hunk
@@ -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?