Reading or writing MSR_IA32_APICBASE is typically an intercepted
operation and causes #VC exception when the test is launched as
an SEV-ES guest.
So calling pre_boot_apic_id() and reset_apic() before the IDT is
set up in setup_idt() and load_idt() might cause problems.
Hence move percpu data setup and reset_apic() call after
setup_idt() and load_idt().
Fixes: 3c50214c97f173f5e0f82c7f248a7c62707d8748 (x86: efi: Provide percpu storage)
Signed-off-by: Vasant Karasulli <vkarasulli@xxxxxxx>
---
lib/x86/setup.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/lib/x86/setup.c b/lib/x86/setup.c
index 7df0256..712e292 100644
--- a/lib/x86/setup.c
+++ b/lib/x86/setup.c
@@ -192,8 +192,6 @@ static void setup_segments64(void)
write_gs(KERNEL_DS);
write_ss(KERNEL_DS);
- /* Setup percpu base */
- wrmsr(MSR_GS_BASE, (u64)&__percpu_data[pre_boot_apic_id()]);
/*
* Update the code segment by putting it on the stack before the return
@@ -322,7 +320,7 @@ efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
}
return status;
}
-
+
status = setup_rsdp(efi_bootinfo);
if (status != EFI_SUCCESS) {
printf("Cannot find RSDP in EFI system table\n");
@@ -344,14 +342,20 @@ efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
}
setup_gdt_tss();
- /*
- * GS.base, which points at the per-vCPU data, must be configured prior
- * to resetting the APIC, which sets the per-vCPU APIC ops.
- */
setup_segments64();
- reset_apic();
setup_idt();
load_idt();
+ /*
+ * Load GS.base with the per-vCPU data. This must be done after
+ * loading the IDT as reading the APIC ID may #VC when running
+ * as an SEV-ES guest
+ */
+ wrmsr(MSR_GS_BASE, (u64)&__percpu_data[pre_boot_apic_id()]);
+ /*
+ * Resetting the APIC sets the per-vCPU APIC ops and so must be
+ * done after loading GS.base with the per-vCPU data.
+ */
+ reset_apic();
mask_pic_interrupts();
setup_page_table();
enable_apic();
--
2.34.1
