lguest, x86: handle guest TS bit for lazy/non-lazy fpu host models
Instead of using unlazy_fpu() check if user_has_fpu() and set/clear
the host TS bits so that the lguest works fine with both the
lazy/non-lazy FPU host models with minimal changes.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-6-git-send-email-suresh.b.siddha@intel.com
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index 39809035..4af12e1 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -203,8 +203,8 @@
* we set it now, so we can trap and pass that trap to the Guest if it
* uses the FPU.
*/
- if (cpu->ts)
- unlazy_fpu(current);
+ if (cpu->ts && user_has_fpu())
+ stts();
/*
* SYSENTER is an optimized way of doing system calls. We can't allow
@@ -234,6 +234,10 @@
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
+ /* Clear the host TS bit if it was set above. */
+ if (cpu->ts && user_has_fpu())
+ clts();
+
/*
* If the Guest page faulted, then the cr2 register will tell us the
* bad virtual address. We have to grab this now, because once we
@@ -249,7 +253,7 @@
* a different CPU. So all the critical stuff should be done
* before this.
*/
- else if (cpu->regs->trapnum == 7)
+ else if (cpu->regs->trapnum == 7 && !user_has_fpu())
math_state_restore();
}