[PATCH 15/55] arm64: KVM: Runtime detection of lower HYP offset

Marc Zyngier
2016-07-22T17:30:16Z

Add the code that enables the switch to the lower HYP VA range.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
arch/arm64/kernel/cpufeature.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 811773d..ffb3e14 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -726,6 +726,19 @@ static bool runs_at_el2(const struct arm64_cpu_capabilities *entry, int __unused
return is_kernel_in_hyp_mode();
}

+static bool hyp_offset_low(const struct arm64_cpu_capabilities *entry,
+ int __unused)
+{
+ phys_addr_t idmap_addr = virt_to_phys(__hyp_idmap_text_start);
+
+ /*
+ * Activate the lower HYP offset only if:
+ * - the idmap doesn't clash with it,
+ * - the kernel is not running at EL2.
+ */
+ return idmap_addr > GENMASK(VA_BITS - 2, 0) && !is_kernel_in_hyp_mode();
+}
+
static const struct arm64_cpu_capabilities arm64_features[] = {
{
.desc = "GIC system register CPU interface",
@@ -803,6 +816,12 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.field_pos = ID_AA64PFR0_EL0_SHIFT,
.min_field_value = ID_AA64PFR0_EL0_32BIT_64BIT,
},
+ {
+ .desc = "Reduced HYP mapping offset",
+ .capability = ARM64_HYP_OFFSET_LOW,
+ .def_scope = SCOPE_SYSTEM,
+ .matches = hyp_offset_low,
+ },
{},
};

--
2.8.1