KVM: ia64: fix fp fault/trap handler
Yang Zhang [Thu, 8 Jan 2009 07:13:31 +0000 (15:13 +0800)]
The floating-point registers f6-f11 is used by vmm and
saved in kvm-pt-regs, so should set the correct bit mask
and the pointer in fp_state, otherwise, fpswa may touch
vmm's fp registers instead of guests'.

In addition, for fp trap handling,  since the instruction
which leads to fp trap is completely executed, so can't
use retry machanism to re-execute it, because it may
pollute some registers.

Signed-off-by: Yang Zhang <yang.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/ia64/kvm/process.c

index 552d077..230eae4 100644 (file)
@@ -455,13 +455,18 @@ fpswa_ret_t vmm_fp_emulate(int fp_fault, void *bundle, unsigned long *ipsr,
        if (!vmm_fpswa_interface)
                return (fpswa_ret_t) {-1, 0, 0, 0};
 
-       /*
-        * Just let fpswa driver to use hardware fp registers.
-        * No fp register is valid in memory.
-        */
        memset(&fp_state, 0, sizeof(fp_state_t));
 
        /*
+        * compute fp_state.  only FP registers f6 - f11 are used by the
+        * vmm, so set those bits in the mask and set the low volatile
+        * pointer to point to these registers.
+        */
+       fp_state.bitmask_low64 = 0xfc0;  /* bit6..bit11 */
+
+       fp_state.fp_state_low_volatile = (fp_state_low_volatile_t *) &regs->f6;
+
+   /*
         * unsigned long (*EFI_FPSWA) (
         *      unsigned long    trap_type,
         *      void             *Bundle,
@@ -545,10 +550,6 @@ void reflect_interruption(u64 ifa, u64 isr, u64 iim,
                status = vmm_handle_fpu_swa(0, regs, isr);
                if (!status)
                        return ;
-               else if (-EAGAIN == status) {
-                       vcpu_decrement_iip(vcpu);
-                       return ;
-               }
                break;
        }