ARM: KVM: Add SMCCC_ARCH_WORKAROUND_1 fast handling

We want SMCCC_ARCH_WORKAROUND_1 to be fast. As fast as possible.
So let's intercept it as early as we can by testing for the
function call number as soon as we've identified a HVC call
coming from the guest.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Boot-tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/arch/arm/kvm/hyp/hyp-entry.S b/arch/arm/kvm/hyp/hyp-entry.S
index 918a05dd2d63..aa3f9a9837ac 100644
--- a/arch/arm/kvm/hyp/hyp-entry.S
+++ b/arch/arm/kvm/hyp/hyp-entry.S
@@ -16,6 +16,7 @@
  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+#include <linux/arm-smccc.h>
 #include <linux/linkage.h>
 #include <asm/kvm_arm.h>
 #include <asm/kvm_asm.h>
@@ -202,7 +203,7 @@ hyp_hvc:
         lsr     r2, r2, #16
         and     r2, r2, #0xff
         cmp     r2, #0
-        bne     guest_trap              @ Guest called HVC
+        bne     guest_hvc_trap          @ Guest called HVC
 
         /*
          * Getting here means host called HVC, we shift parameters and branch
@@ -253,6 +254,20 @@ THUMB(	orr	lr, #1)
         pop     {r2, lr}
         eret
 
+guest_hvc_trap:
+        movw    r2, #:lower16:ARM_SMCCC_ARCH_WORKAROUND_1
+        movt    r2, #:upper16:ARM_SMCCC_ARCH_WORKAROUND_1
+        ldr     r0, [sp]                @ Guest's r0
+        teq     r0, r2
+        bne     guest_trap
+        add     sp, sp, #12
+        @ Returns:
+        @ r0 = 0
+        @ r1 = HSR value (perfectly predictable)
+        @ r2 = ARM_SMCCC_ARCH_WORKAROUND_1
+        mov     r0, #0
+        eret
+
 guest_trap:
         load_vcpu r0                    @ Load VCPU pointer to r0