arm64: KVM: Dynamically compute the HYP VA mask

As we're moving towards a much more dynamic way to compute our
HYP VA, let's express the mask in a slightly different way.

Instead of comparing the idmap position to the "low" VA mask,
we directly compute the mask by taking into account the idmap's
(VA_BIT-1) bit.

No functionnal change.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/kvm/va_layout.c b/arch/arm64/kvm/va_layout.c
index 0d7bf831989473601832840b1622ffaec95e58d5..7998d1a60916241c4ad9f793b64b7d4ab1f9622a 100644 (file)
--- a/arch/arm64/kvm/va_layout.c
+++ b/arch/arm64/kvm/va_layout.c
@@ -21,24 +21,19 @@
 #include <asm/insn.h>
 #include <asm/kvm_mmu.h>
 
-#define HYP_PAGE_OFFSET_HIGH_MASK      ((UL(1) << VA_BITS) - 1)
-#define HYP_PAGE_OFFSET_LOW_MASK       ((UL(1) << (VA_BITS - 1)) - 1)
-
 static u64 va_mask;
 
 static void compute_layout(void)
 {
        phys_addr_t idmap_addr = __pa_symbol(__hyp_idmap_text_start);
-       unsigned long mask = HYP_PAGE_OFFSET_HIGH_MASK;
+       u64 hyp_va_msb;
 
-       /*
-        * Activate the lower HYP offset only if the idmap doesn't
-        * clash with it,
-        */
-       if (idmap_addr > HYP_PAGE_OFFSET_LOW_MASK)
-               mask = HYP_PAGE_OFFSET_LOW_MASK;
+       /* Where is my RAM region? */
+       hyp_va_msb  = idmap_addr & BIT(VA_BITS - 1);
+       hyp_va_msb ^= BIT(VA_BITS - 1);
 
-       va_mask = mask;
+       va_mask  = GENMASK_ULL(VA_BITS - 2, 0);
+       va_mask |= hyp_va_msb;
 }
 
 static u32 compute_instruction(int n, u32 rd, u32 rn)