ARM: KVM: Implement HVC_RESET_VECTORS stub hypercall in the init code

In order to restore HYP mode to its original condition, KVM currently
implements __kvm_hyp_reset(). As we're moving towards a hyp-stub
defined API, it becomes necessary to implement HVC_RESET_VECTORS.

This patch adds the HVC_RESET_VECTORS hypercall to the KVM init
code, which so far lacked any form of hypercall support.

Tested-by: Keerthy <j-keerthy@ti.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>

diff --git a/arch/arm/include/asm/virt.h b/arch/arm/include/asm/virt.h
index c5a2757..663adc0 100644 (file)
--- a/arch/arm/include/asm/virt.h
+++ b/arch/arm/include/asm/virt.h
@@ -54,6 +54,7 @@ static inline void sync_boot_mode(void)
 
 void __hyp_set_vectors(unsigned long phys_vector_base);
 unsigned long __hyp_get_vectors(void);
+void __hyp_reset_vectors(void);
 #else
 #define __boot_cpu_mode        (SVC_MODE)
 #define sync_boot_mode()

diff --git a/arch/arm/kernel/hyp-stub.S b/arch/arm/kernel/hyp-stub.S
index e637854..675c50f 100644 (file)
--- a/arch/arm/kernel/hyp-stub.S
+++ b/arch/arm/kernel/hyp-stub.S
@@ -280,7 +280,7 @@ ENDPROC(__hyp_reset_vectors)
 #endif
 
 .align 5
-__hyp_stub_vectors:
+ENTRY(__hyp_stub_vectors)
 __hyp_stub_reset:      W(b)    .
 __hyp_stub_und:                W(b)    .
 __hyp_stub_svc:                W(b)    .

diff --git a/arch/arm/kvm/init.S b/arch/arm/kvm/init.S
index bf89c91..86a7008 100644 (file)
--- a/arch/arm/kvm/init.S
+++ b/arch/arm/kvm/init.S
@@ -23,6 +23,7 @@
 #include <asm/kvm_asm.h>
 #include <asm/kvm_arm.h>
 #include <asm/kvm_mmu.h>
+#include <asm/virt.h>
 
 /********************************************************************
  * Hypervisor initialization
@@ -39,6 +40,10 @@
  * - Setup the page tables
  * - Enable the MMU
  * - Profit! (or eret, if you only care about the code).
+ *
+ * Another possibility is to get a HYP stub hypercall.
+ * We discriminate between the two by checking if r0 contains a value
+ * that is less than HVC_STUB_HCALL_NR.
  */
 
        .text
@@ -58,6 +63,10 @@ __kvm_hyp_init:
        W(b)    .
 
 __do_hyp_init:
+       @ Check for a stub hypercall
+       cmp     r0, #HVC_STUB_HCALL_NR
+       blo     __kvm_handle_stub_hvc
+
        @ Set stack pointer
        mov     sp, r0
 
@@ -112,19 +121,31 @@ __do_hyp_init:
 
        eret
 
-       @ r0 : stub vectors address
+ENTRY(__kvm_handle_stub_hvc)
+       cmp     r0, #HVC_RESET_VECTORS
+       bne     1f
 ENTRY(__kvm_hyp_reset)
        /* We're now in idmap, disable MMU */
        mrc     p15, 4, r1, c1, c0, 0   @ HSCTLR
-       ldr     r2, =(HSCTLR_M | HSCTLR_A | HSCTLR_C | HSCTLR_I)
-       bic     r1, r1, r2
+       ldr     r0, =(HSCTLR_M | HSCTLR_A | HSCTLR_C | HSCTLR_I)
+       bic     r1, r1, r0
        mcr     p15, 4, r1, c1, c0, 0   @ HSCTLR
 
-       /* Install stub vectors */
-       mcr     p15, 4, r0, c12, c0, 0  @ HVBAR
-       isb
+       /*
+        * Install stub vectors, using ardb's VA->PA trick.
+        */
+0:     adr     r0, 0b                                  @ PA(0)
+       movw    r1, #:lower16:__hyp_stub_vectors - 0b   @ VA(stub) - VA(0)
+       movt    r1, #:upper16:__hyp_stub_vectors - 0b
+       add     r1, r1, r0                              @ PA(stub)
+       mcr     p15, 4, r1, c12, c0, 0  @ HVBAR
+       b       exit
+
+1:     ldr     r0, =HVC_STUB_ERR
 
+exit:
        eret
+ENDPROC(__kvm_handle_stub_hvc)
 ENDPROC(__kvm_hyp_reset)
 
        .ltorg