arm64: Factor out checking of a feature against the override into a macro

Checking for a feature being supported from assembly code is
a bit tedious if we need to factor in the idreg override.

Since we already have such code written for forcing nVHE, move
the whole thing into a macro. This heavily relies on the override
structure being called foo_override for foo_el1.

No functional change.

Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220630160500.1536744-5-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index 571286e..43c94e7 100644 (file)
--- a/arch/arm64/kernel/hyp-stub.S
+++ b/arch/arm64/kernel/hyp-stub.S
@@ -16,6 +16,25 @@
 #include <asm/ptrace.h>
 #include <asm/virt.h>
 
+// Warning, hardcoded register allocation
+// This will clobber x1 and x2.
+.macro check_override idreg, fld, pass, fail
+       mrs     x1, \idreg\()_el1
+       ubfx    x1, x1, #\fld, #4
+       cbz     x1, \fail
+
+       adr_l   x1, \idreg\()_override
+       ldr     x2, [x1, FTR_OVR_VAL_OFFSET]
+       ldr     x1, [x1, FTR_OVR_MASK_OFFSET]
+       ubfx    x2, x2, #\fld, #4
+       ubfx    x1, x1, #\fld, #4
+       cmp     x1, xzr
+       and     x2, x2, x1
+       csinv   x2, x2, xzr, ne
+       cbnz    x2, \pass
+       b       \fail
+.endm
+
        .text
        .pushsection    .hyp.text, "ax"
 
@@ -80,20 +99,7 @@ SYM_CODE_START_LOCAL(__finalise_el2)
        tbnz    x1, #0, 1f
 
        // Needs to be VHE capable, obviously
-       mrs     x1, id_aa64mmfr1_el1
-       ubfx    x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4
-       cbz     x1, 1f
-
-       // Check whether VHE is disabled from the command line
-       adr_l   x1, id_aa64mmfr1_override
-       ldr     x2, [x1, FTR_OVR_VAL_OFFSET]
-       ldr     x1, [x1, FTR_OVR_MASK_OFFSET]
-       ubfx    x2, x2, #ID_AA64MMFR1_VHE_SHIFT, #4
-       ubfx    x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4
-       cmp     x1, xzr
-       and     x2, x2, x1
-       csinv   x2, x2, xzr, ne
-       cbnz    x2, 2f
+       check_override id_aa64mmfr1 ID_AA64MMFR1_VHE_SHIFT 2f 1f
 
 1:     mov_q   x0, HVC_STUB_ERR
        eret