From: Roger Pau Monne <roger.pau@citrix.com>
Date: Mon, 17 Aug 2020 15:57:54 +0000 (+0200)
Subject: x86/pv: allow reading APIC_BASE MSR
X-Git-Tag: archive/raspbian/4.16.0+51-g0941d6cb-1+rpi1~2^2~42^2~1757
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=a825751f633482c0634ebb7c7b7ba33acadcfe7b;p=xen.git

x86/pv: allow reading APIC_BASE MSR

Linux PV guests will attempt to read the APIC_BASE MSR, so just report
a default value to make Linux happy.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/xen/arch/x86/pv/emul-priv-op.c b/xen/arch/x86/pv/emul-priv-op.c
index 971ba9e58c..bcc1188f6a 100644
--- a/xen/arch/x86/pv/emul-priv-op.c
+++ b/xen/arch/x86/pv/emul-priv-op.c
@@ -872,6 +872,13 @@ static int read_msr(unsigned int reg, uint64_t *val,
 
     switch ( reg )
     {
+    case MSR_APIC_BASE:
+        /* Linux PV guests will attempt to read APIC_BASE. */
+        *val = APIC_BASE_ENABLE | APIC_DEFAULT_PHYS_BASE;
+        if ( !curr->vcpu_id )
+            *val |= APIC_BASE_BSP;
+        return X86EMUL_OKAY;
+
     case MSR_FS_BASE:
         if ( is_pv_32bit_domain(currd) )
             break;