[PATCH v4 2/6] RISC-V: add vector crypto extension validation checks

[Conor Dooley <conor@kernel.org>]

From: Conor Dooley <conor.dooley@microchip.com>

Using Clement's new validation callbacks, support checking that
dependencies have been satisfied for the vector crpyto extensions.
Currently riscv_isa_extension_available(<vector crypto>) will return
true on systems that support the extensions but vector itself has been
disabled by the kernel, adding validation callbacks will prevent such a
scenario from occuring and make the behaviour of the extension detection
functions more consistent with user expectations - it's not expected to
have to check for vector AND the specific crypto extension.

The Unpriv spec states:
| The Zvknhb and Zvbc Vector Crypto Extensions --and accordingly the
| composite extensions Zvkn, Zvknc, Zvkng, and Zvksc-- require a Zve64x
| base, or application ("V") base Vector Extension. All of the other
| Vector Crypto Extensions can be built on any embedded (Zve*) or
| application ("V") base Vector Extension.

While this could be used as the basis for checking that the correct base
for individual crypto extensions, but that's not really the kernel's job
in my opinion and it is sufficient to leave that sort of precision to
the dt-bindings. The kernel only needs to make sure that vector, in some
form, is available.

Link: https://github.com/riscv/riscv-isa-manual/blob/main/src/vector-crypto.adoc#extensions-overview
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
 arch/riscv/kernel/cpufeature.c | 49 +++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 16 deletions(-)

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index dbea6ed3f4da..4fa951e9f1cf 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -141,6 +141,23 @@ static int riscv_ext_vector_float_validate(const struct riscv_isa_ext_data *data
 	return 0;
 }
 
+static int riscv_ext_vector_crypto_validate(const struct riscv_isa_ext_data *data,
+					    const unsigned long *isa_bitmap)
+{
+	if (!IS_ENABLED(CONFIG_RISCV_ISA_V))
+		return -EINVAL;
+
+	/*
+	 * It isn't the kernel's job to check that the binding is correct, so
+	 * it should be enough to check that any of the vector extensions are
+	 * enabled, which in-turn means that vector is usable in this kernel
+	 */
+	if (!__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZVE32X))
+		return -EPROBE_DEFER;
+
+	return 0;
+}
+
 static int riscv_ext_zca_depends(const struct riscv_isa_ext_data *data,
 				 const unsigned long *isa_bitmap)
 {
@@ -400,8 +417,8 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(zksed, RISCV_ISA_EXT_ZKSED),
 	__RISCV_ISA_EXT_DATA(zksh, RISCV_ISA_EXT_ZKSH),
 	__RISCV_ISA_EXT_DATA(ztso, RISCV_ISA_EXT_ZTSO),
-	__RISCV_ISA_EXT_SUPERSET(zvbb, RISCV_ISA_EXT_ZVBB, riscv_zvbb_exts),
-	__RISCV_ISA_EXT_DATA(zvbc, RISCV_ISA_EXT_ZVBC),
+	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zvbb, RISCV_ISA_EXT_ZVBB, riscv_zvbb_exts, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvbc, RISCV_ISA_EXT_ZVBC, riscv_ext_vector_crypto_validate),
 	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zve32f, RISCV_ISA_EXT_ZVE32F, riscv_zve32f_exts, riscv_ext_vector_float_validate),
 	__RISCV_ISA_EXT_DATA_VALIDATE(zve32x, RISCV_ISA_EXT_ZVE32X, riscv_ext_vector_x_validate),
 	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zve64d, RISCV_ISA_EXT_ZVE64D, riscv_zve64d_exts, riscv_ext_vector_float_validate),
@@ -409,20 +426,20 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zve64x, RISCV_ISA_EXT_ZVE64X, riscv_zve64x_exts, riscv_ext_vector_x_validate),
 	__RISCV_ISA_EXT_DATA(zvfh, RISCV_ISA_EXT_ZVFH),
 	__RISCV_ISA_EXT_DATA(zvfhmin, RISCV_ISA_EXT_ZVFHMIN),
-	__RISCV_ISA_EXT_DATA(zvkb, RISCV_ISA_EXT_ZVKB),
-	__RISCV_ISA_EXT_DATA(zvkg, RISCV_ISA_EXT_ZVKG),
-	__RISCV_ISA_EXT_BUNDLE(zvkn, riscv_zvkn_bundled_exts),
-	__RISCV_ISA_EXT_BUNDLE(zvknc, riscv_zvknc_bundled_exts),
-	__RISCV_ISA_EXT_DATA(zvkned, RISCV_ISA_EXT_ZVKNED),
-	__RISCV_ISA_EXT_BUNDLE(zvkng, riscv_zvkng_bundled_exts),
-	__RISCV_ISA_EXT_DATA(zvknha, RISCV_ISA_EXT_ZVKNHA),
-	__RISCV_ISA_EXT_DATA(zvknhb, RISCV_ISA_EXT_ZVKNHB),
-	__RISCV_ISA_EXT_BUNDLE(zvks, riscv_zvks_bundled_exts),
-	__RISCV_ISA_EXT_BUNDLE(zvksc, riscv_zvksc_bundled_exts),
-	__RISCV_ISA_EXT_DATA(zvksed, RISCV_ISA_EXT_ZVKSED),
-	__RISCV_ISA_EXT_DATA(zvksh, RISCV_ISA_EXT_ZVKSH),
-	__RISCV_ISA_EXT_BUNDLE(zvksg, riscv_zvksg_bundled_exts),
-	__RISCV_ISA_EXT_DATA(zvkt, RISCV_ISA_EXT_ZVKT),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvkb, RISCV_ISA_EXT_ZVKB, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvkg, RISCV_ISA_EXT_ZVKG, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvkn, riscv_zvkn_bundled_exts, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvknc, riscv_zvknc_bundled_exts, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvkned, RISCV_ISA_EXT_ZVKNED, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvkng, riscv_zvkng_bundled_exts, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvknha, RISCV_ISA_EXT_ZVKNHA, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvknhb, RISCV_ISA_EXT_ZVKNHB, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvks, riscv_zvks_bundled_exts, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvksc, riscv_zvksc_bundled_exts, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvksed, RISCV_ISA_EXT_ZVKSED, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvksh, RISCV_ISA_EXT_ZVKSH, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvksg, riscv_zvksg_bundled_exts, riscv_ext_vector_crypto_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvkt, RISCV_ISA_EXT_ZVKT, riscv_ext_vector_crypto_validate),
 	__RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
 	__RISCV_ISA_EXT_DATA(smmpm, RISCV_ISA_EXT_SMMPM),
 	__RISCV_ISA_EXT_SUPERSET(smnpm, RISCV_ISA_EXT_SMNPM, riscv_xlinuxenvcfg_exts),
-- 
2.45.2