x86/hvm: Rework HVM_HCALL_invalidate handling

Sending an invalidation to the device model is an internal detail of
completing the hypercall; callers should not need to be responsible for it.
Drop HVM_HCALL_invalidate entirely and call send_invalidate_req() when
appropriate.

This makes the function boolean in nature, although the existing
HVM_HCALL_{completed,preempted} constants are kept to aid code clarity.  While
updating the return type, drop _do from the name, as it is redundant.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>

xen/arch/x86/hvm/hvm.c

@@ -3874,7 +3874,7 @@ static const hypercall_table_t hvm_hypercall_table[] = {
 #undef HYPERCALL
 #undef COMPAT_CALL
 
-int hvm_do_hypercall(struct cpu_user_regs *regs)
+int hvm_hypercall(struct cpu_user_regs *regs)
 {
     struct vcpu *curr = current;
     struct domain *currd = curr->domain;
@@ -4011,9 +4011,8 @@ int hvm_do_hypercall(struct cpu_user_regs *regs)
         return HVM_HCALL_preempted;
 
     if ( unlikely(currd->arch.hvm_domain.qemu_mapcache_invalidate) &&
-         test_and_clear_bool(currd->arch.hvm_domain.
-                             qemu_mapcache_invalidate) )
-        return HVM_HCALL_invalidate;
+         test_and_clear_bool(currd->arch.hvm_domain.qemu_mapcache_invalidate) )
+        send_invalidate_req();
 
     return HVM_HCALL_completed;
 }

xen/arch/x86/hvm/svm/svm.c

@@ -2542,13 +2542,9 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
             break;
         BUG_ON(vcpu_guestmode);
         HVMTRACE_1D(VMMCALL, regs->_eax);
-        rc = hvm_do_hypercall(regs);
-        if ( rc != HVM_HCALL_preempted )
-        {
+
+        if ( hvm_hypercall(regs) == HVM_HCALL_completed )
             __update_guest_eip(regs, inst_len);
-            if ( rc == HVM_HCALL_invalidate )
-                send_invalidate_req();
-        }
         break;
 
     case VMEXIT_DR0_READ ... VMEXIT_DR7_READ:

xen/arch/x86/hvm/vmx/vmx.c

@@ -3629,19 +3629,14 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
         update_guest_eip(); /* Safe: RDTSC, RDTSCP */
         hvm_rdtsc_intercept(regs);
         break;
+
     case EXIT_REASON_VMCALL:
-    {
-        int rc;
         HVMTRACE_1D(VMMCALL, regs->_eax);
-        rc = hvm_do_hypercall(regs);
-        if ( rc != HVM_HCALL_preempted )
-        {
+
+        if ( hvm_hypercall(regs) == HVM_HCALL_completed )
             update_guest_eip(); /* Safe: VMCALL */
-            if ( rc == HVM_HCALL_invalidate )
-                send_invalidate_req();
-        }
         break;
-    }
+
     case EXIT_REASON_CR_ACCESS:
     {
         __vmread(EXIT_QUALIFICATION, &exit_qualification);

xen/include/asm-x86/hvm/support.h

@@ -105,8 +105,7 @@ enum hvm_copy_result hvm_fetch_from_guest_linear(
 
 #define HVM_HCALL_completed  0 /* hypercall completed - no further action */
 #define HVM_HCALL_preempted  1 /* hypercall preempted - re-execute VMCALL */
-#define HVM_HCALL_invalidate 2 /* invalidate ioemu-dm memory cache        */
-int hvm_do_hypercall(struct cpu_user_regs *pregs);
+int hvm_hypercall(struct cpu_user_regs *regs);
 
 void hvm_hlt(unsigned int eflags);
 void hvm_triple_fault(void);