arm64/boot: Disable trapping of PMZR_EL0 writes to EL2grafted

__init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2.
PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in
HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host
traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The
kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU
driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a
write from EL0 reaches the trap and takes the host down without a panic
message.

Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already
does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9
bits.

Fixes: 858c7bfcb35e1 ("arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9")
Cc: stable@vger.kernel.org
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 98 insertions, 0 deletions

diff --git a/include/crypto/dh.h b/include/crypto/dh.h
new file mode 100644
index 000000000..7b863e911
--- /dev/null
+++ b/include/crypto/dh.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Diffie-Hellman secret to be used with kpp API along with helper functions
+ *
+ * Copyright (c) 2016, Intel Corporation
+ * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
+ */
+#ifndef _CRYPTO_DH_
+#define _CRYPTO_DH_
+
+/**
+ * DOC: DH Helper Functions
+ *
+ * To use DH with the KPP cipher API, the following data structure and
+ * functions should be used.
+ *
+ * To use DH with KPP, the following functions should be used to operate on
+ * a DH private key. The packet private key that can be set with
+ * the KPP API function call of crypto_kpp_set_secret.
+ */
+
+/**
+ * struct dh - define a DH private key
+ *
+ * @key:	Private DH key
+ * @p:		Diffie-Hellman parameter P
+ * @g:		Diffie-Hellman generator G
+ * @key_size:	Size of the private DH key
+ * @p_size:	Size of DH parameter P
+ * @g_size:	Size of DH generator G
+ */
+struct dh {
+	const void *key;
+	const void *p;
+	const void *g;
+	unsigned int key_size;
+	unsigned int p_size;
+	unsigned int g_size;
+};
+
+/**
+ * crypto_dh_key_len() - Obtain the size of the private DH key
+ * @params:	private DH key
+ *
+ * This function returns the packet DH key size. A caller can use that
+ * with the provided DH private key reference to obtain the required
+ * memory size to hold a packet key.
+ *
+ * Return: size of the key in bytes
+ */
+unsigned int crypto_dh_key_len(const struct dh *params);
+
+/**
+ * crypto_dh_encode_key() - encode the private key
+ * @buf:	Buffer allocated by the caller to hold the packet DH
+ *		private key. The buffer should be at least crypto_dh_key_len
+ *		bytes in size.
+ * @len:	Length of the packet private key buffer
+ * @params:	Buffer with the caller-specified private key
+ *
+ * The DH implementations operate on a packet representation of the private
+ * key.
+ *
+ * Return:	-EINVAL if buffer has insufficient size, 0 on success
+ */
+int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params);
+
+/**
+ * crypto_dh_decode_key() - decode a private key
+ * @buf:	Buffer holding a packet key that should be decoded
+ * @len:	Length of the packet private key buffer
+ * @params:	Buffer allocated by the caller that is filled with the
+ *		unpacked DH private key.
+ *
+ * The unpacking obtains the private key by pointing @p to the correct location
+ * in @buf. Thus, both pointers refer to the same memory.
+ *
+ * Return:	-EINVAL if buffer has insufficient size, 0 on success
+ */
+int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params);
+
+/**
+ * __crypto_dh_decode_key() - decode a private key without parameter checks
+ * @buf:	Buffer holding a packet key that should be decoded
+ * @len:	Length of the packet private key buffer
+ * @params:	Buffer allocated by the caller that is filled with the
+ *		unpacked DH private key.
+ *
+ * Internal function providing the same services as the exported
+ * crypto_dh_decode_key(), but without any of those basic parameter
+ * checks conducted by the latter.
+ *
+ * Return:	-EINVAL if buffer has insufficient size, 0 on success
+ */
+int __crypto_dh_decode_key(const char *buf, unsigned int len,
+			   struct dh *params);
+
+#endif