File xsa377.patch of Package xen.21119

From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: x86/spec-ctrl: Mitigate TAA after S3 resume

The user chosen setting for MSR_TSX_CTRL needs restoring after S3.

All APs get the correct setting via start_secondary(), but the BSP was missed
out.

This is XSA-377 / CVE-2021-28690.

Fixes: 8c4330818f6 ("x86/spec-ctrl: Mitigate the TSX Asynchronous Abort sidechannel")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/acpi/power.c
+++ b/xen/arch/x86/acpi/power.c
@@ -255,6 +255,8 @@ static int enter_state(u32 state)
 
     microcode_resume_cpu(0);
 
+    tsx_init(); /* Needs microcode.  May change HLE/RTM feature bits. */
+
     /* Re-enabled default NMI/#MC use of MSR_SPEC_CTRL. */
     ci->spec_ctrl_flags |= (default_spec_ctrl_flags & SCF_ist_wrmsr);
     spec_ctrl_exit_idle(ci);