MIPS: KVM: Don't hardcode restored HWREna

KVM modifies CP0_HWREna during guest execution so it can trap and
emulate RDHWR instructions, however it always restores the hardcoded
value 0x2000000F. This assumes the presence of the UserLocal register,
and the absence of any implementation dependent or future HW registers.

Fix by exporting the value that traps.c write into CP0_HWREna, and
loading from there instead of hard coding.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/mips/include/asm/setup.h b/arch/mips/include/asm/setup.h
index d7bfdeb..4f5279a 100644 (file)
--- a/arch/mips/include/asm/setup.h
+++ b/arch/mips/include/asm/setup.h
@@ -21,6 +21,7 @@ extern void *set_vi_handler(int n, vi_handler_t addr);
 
 extern void *set_except_vector(int n, void *addr);
 extern unsigned long ebase;
+extern unsigned int hwrena;
 extern void per_cpu_trap_init(bool);
 extern void cpu_cache_init(void);
 

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 7176a60..6fb4704 100644 (file)
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -2064,10 +2064,13 @@ static void configure_status(void)
                         status_set);
 }
 
+unsigned int hwrena;
+EXPORT_SYMBOL_GPL(hwrena);
+
 /* configure HWRENA register */
 static void configure_hwrena(void)
 {
-       unsigned int hwrena = cpu_hwrena_impl_bits;
+       hwrena = cpu_hwrena_impl_bits;
 
        if (cpu_has_mips_r2_r6)
                hwrena |= MIPS_HWRENA_CPUNUM |

diff --git a/arch/mips/kvm/locore.S b/arch/mips/kvm/locore.S
index f87bec5..698286c 100644 (file)
--- a/arch/mips/kvm/locore.S
+++ b/arch/mips/kvm/locore.S
@@ -381,7 +381,7 @@ NESTED (MIPSX(GuestException), CALLFRAME_SIZ, ra)
        mtc0    k0, CP0_DDATA_LO
 
        /* Restore RDHWR access */
-       PTR_LI  k0, 0x2000000F
+       INT_L   k0, hwrena
        mtc0    k0, CP0_HWRENA
 
        /* Jump to handler */
@@ -553,7 +553,7 @@ __kvm_mips_return_to_host:
        mtlo    k0
 
        /* Restore RDHWR access */
-       PTR_LI  k0, 0x2000000F
+       INT_L   k0, hwrena
        mtc0    k0, CP0_HWRENA
 
        /* Restore RA, which is the address we will return to */