KVM: Be more careful restoring fs on lightweight vmexit

i386 wants fs for accessing the pda even on a lightweight exit, so ensure
we can always restore it.  This fixes a regression on i386 introduced by
the lightweight vmexit patch.

Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 11 insertions, 11 deletions

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 9ebb18d07bde..49cadd31120b 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1832,16 +1832,21 @@ preempted:
          * Set host fs and gs selectors.  Unfortunately, 22.2.3 does not
          * allow segment selectors with cpl > 0 or ti == 1.
          */
-        fs_sel = read_fs();
-        gs_sel = read_gs();
         ldt_sel = read_ldt();
-        fs_gs_ldt_reload_needed = (fs_sel & 7) | (gs_sel & 7) | ldt_sel;
-        if (!fs_gs_ldt_reload_needed) {
+        fs_gs_ldt_reload_needed = ldt_sel;
+        fs_sel = read_fs();
+        if (!(fs_sel & 7))
                 vmcs_write16(HOST_FS_SELECTOR, fs_sel);
-                vmcs_write16(HOST_GS_SELECTOR, gs_sel);
-        } else {
+        else {
                 vmcs_write16(HOST_FS_SELECTOR, 0);
+                fs_gs_ldt_reload_needed = 1;
+        }
+        gs_sel = read_gs();
+        if (!(gs_sel & 7))
+                vmcs_write16(HOST_GS_SELECTOR, gs_sel);
+        else {
                 vmcs_write16(HOST_GS_SELECTOR, 0);
+                fs_gs_ldt_reload_needed = 1;
         }
 
 #ifdef CONFIG_X86_64
@@ -2035,11 +2040,6 @@ again:
         }
 
 out:
-        /*
-         * Reload segment selectors ASAP. (it's needed for a functional
-         * kernel: x86 relies on having __KERNEL_PDA in %fs and x86_64
-         * relies on having 0 in %gs for the CPU PDA to work.)
-         */
         if (fs_gs_ldt_reload_needed) {
                 load_ldt(ldt_sel);
                 load_fs(fs_sel);