cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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vphn.c (2499B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <asm/byteorder.h>
      3#include <asm/lppaca.h>
      4
      5/*
      6 * The associativity domain numbers are returned from the hypervisor as a
      7 * stream of mixed 16-bit and 32-bit fields. The stream is terminated by the
      8 * special value of "all ones" (aka. 0xffff) and its size may not exceed 48
      9 * bytes.
     10 *
     11 *    --- 16-bit fields -->
     12 *  _________________________
     13 *  |  0  |  1  |  2  |  3  |   be_packed[0]
     14 *  ------+-----+-----+------
     15 *  _________________________
     16 *  |  4  |  5  |  6  |  7  |   be_packed[1]
     17 *  -------------------------
     18 *            ...
     19 *  _________________________
     20 *  | 20  | 21  | 22  | 23  |   be_packed[5]
     21 *  -------------------------
     22 *
     23 * Convert to the sequence they would appear in the ibm,associativity property.
     24 */
     25static int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
     26{
     27	__be64 be_packed[VPHN_REGISTER_COUNT];
     28	int i, nr_assoc_doms = 0;
     29	const __be16 *field = (const __be16 *) be_packed;
     30	u16 last = 0;
     31	bool is_32bit = false;
     32
     33#define VPHN_FIELD_UNUSED	(0xffff)
     34#define VPHN_FIELD_MSB		(0x8000)
     35#define VPHN_FIELD_MASK		(~VPHN_FIELD_MSB)
     36
     37	/* Let's fix the values returned by plpar_hcall9() */
     38	for (i = 0; i < VPHN_REGISTER_COUNT; i++)
     39		be_packed[i] = cpu_to_be64(packed[i]);
     40
     41	for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) {
     42		u16 new = be16_to_cpup(field++);
     43
     44		if (is_32bit) {
     45			/*
     46			 * Let's concatenate the 16 bits of this field to the
     47			 * 15 lower bits of the previous field
     48			 */
     49			unpacked[++nr_assoc_doms] =
     50				cpu_to_be32(last << 16 | new);
     51			is_32bit = false;
     52		} else if (new == VPHN_FIELD_UNUSED)
     53			/* This is the list terminator */
     54			break;
     55		else if (new & VPHN_FIELD_MSB) {
     56			/* Data is in the lower 15 bits of this field */
     57			unpacked[++nr_assoc_doms] =
     58				cpu_to_be32(new & VPHN_FIELD_MASK);
     59		} else {
     60			/*
     61			 * Data is in the lower 15 bits of this field
     62			 * concatenated with the next 16 bit field
     63			 */
     64			last = new;
     65			is_32bit = true;
     66		}
     67	}
     68
     69	/* The first cell contains the length of the property */
     70	unpacked[0] = cpu_to_be32(nr_assoc_doms);
     71
     72	return nr_assoc_doms;
     73}
     74
     75/* NOTE: This file is included by a selftest and built in userspace. */
     76#ifdef __KERNEL__
     77#include <asm/hvcall.h>
     78
     79long hcall_vphn(unsigned long cpu, u64 flags, __be32 *associativity)
     80{
     81	long rc;
     82	long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};
     83
     84	rc = plpar_hcall9(H_HOME_NODE_ASSOCIATIVITY, retbuf, flags, cpu);
     85	if (rc == H_SUCCESS)
     86		vphn_unpack_associativity(retbuf, associativity);
     87
     88	return rc;
     89}
     90#endif