From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- drivers/char/adi.c | 232 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 232 insertions(+) create mode 100644 drivers/char/adi.c (limited to 'drivers/char/adi.c') diff --git a/drivers/char/adi.c b/drivers/char/adi.c new file mode 100644 index 000000000..0849d933a --- /dev/null +++ b/drivers/char/adi.c @@ -0,0 +1,232 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Privileged ADI driver for sparc64 + * + * Author: Tom Hromatka + */ +#include +#include +#include +#include +#include +#include +#include + +#define MAX_BUF_SZ PAGE_SIZE + +static int read_mcd_tag(unsigned long addr) +{ + long err; + int ver; + + __asm__ __volatile__( + "1: ldxa [%[addr]] %[asi], %[ver]\n" + " mov 0, %[err]\n" + "2:\n" + " .section .fixup,#alloc,#execinstr\n" + " .align 4\n" + "3: sethi %%hi(2b), %%g1\n" + " jmpl %%g1 + %%lo(2b), %%g0\n" + " mov %[invalid], %[err]\n" + " .previous\n" + " .section __ex_table, \"a\"\n" + " .align 4\n" + " .word 1b, 3b\n" + " .previous\n" + : [ver] "=r" (ver), [err] "=r" (err) + : [addr] "r" (addr), [invalid] "i" (EFAULT), + [asi] "i" (ASI_MCD_REAL) + : "memory", "g1" + ); + + if (err) + return -EFAULT; + else + return ver; +} + +static ssize_t adi_read(struct file *file, char __user *buf, + size_t count, loff_t *offp) +{ + size_t ver_buf_sz, bytes_read = 0; + int ver_buf_idx = 0; + loff_t offset; + u8 *ver_buf; + ssize_t ret; + + ver_buf_sz = min_t(size_t, count, MAX_BUF_SZ); + ver_buf = kmalloc(ver_buf_sz, GFP_KERNEL); + if (!ver_buf) + return -ENOMEM; + + offset = (*offp) * adi_blksize(); + + while (bytes_read < count) { + ret = read_mcd_tag(offset); + if (ret < 0) + goto out; + + ver_buf[ver_buf_idx] = (u8)ret; + ver_buf_idx++; + offset += adi_blksize(); + + if (ver_buf_idx >= ver_buf_sz) { + if (copy_to_user(buf + bytes_read, ver_buf, + ver_buf_sz)) { + ret = -EFAULT; + goto out; + } + + bytes_read += ver_buf_sz; + ver_buf_idx = 0; + + ver_buf_sz = min_t(size_t, count - bytes_read, + MAX_BUF_SZ); + } + } + + (*offp) += bytes_read; + ret = bytes_read; +out: + kfree(ver_buf); + return ret; +} + +static int set_mcd_tag(unsigned long addr, u8 ver) +{ + long err; + + __asm__ __volatile__( + "1: stxa %[ver], [%[addr]] %[asi]\n" + " mov 0, %[err]\n" + "2:\n" + " .section .fixup,#alloc,#execinstr\n" + " .align 4\n" + "3: sethi %%hi(2b), %%g1\n" + " jmpl %%g1 + %%lo(2b), %%g0\n" + " mov %[invalid], %[err]\n" + " .previous\n" + " .section __ex_table, \"a\"\n" + " .align 4\n" + " .word 1b, 3b\n" + " .previous\n" + : [err] "=r" (err) + : [ver] "r" (ver), [addr] "r" (addr), + [invalid] "i" (EFAULT), [asi] "i" (ASI_MCD_REAL) + : "memory", "g1" + ); + + if (err) + return -EFAULT; + else + return ver; +} + +static ssize_t adi_write(struct file *file, const char __user *buf, + size_t count, loff_t *offp) +{ + size_t ver_buf_sz, bytes_written = 0; + loff_t offset; + u8 *ver_buf; + ssize_t ret; + int i; + + if (count == 0) + return -EINVAL; + + ver_buf_sz = min_t(size_t, count, MAX_BUF_SZ); + ver_buf = kmalloc(ver_buf_sz, GFP_KERNEL); + if (!ver_buf) + return -ENOMEM; + + offset = (*offp) * adi_blksize(); + + do { + if (copy_from_user(ver_buf, &buf[bytes_written], + ver_buf_sz)) { + ret = -EFAULT; + goto out; + } + + for (i = 0; i < ver_buf_sz; i++) { + ret = set_mcd_tag(offset, ver_buf[i]); + if (ret < 0) + goto out; + + offset += adi_blksize(); + } + + bytes_written += ver_buf_sz; + ver_buf_sz = min_t(size_t, count - bytes_written, MAX_BUF_SZ); + } while (bytes_written < count); + + (*offp) += bytes_written; + ret = bytes_written; +out: + __asm__ __volatile__("membar #Sync"); + kfree(ver_buf); + return ret; +} + +static loff_t adi_llseek(struct file *file, loff_t offset, int whence) +{ + loff_t ret = -EINVAL; + + switch (whence) { + case SEEK_END: + case SEEK_DATA: + case SEEK_HOLE: + /* unsupported */ + return -EINVAL; + case SEEK_CUR: + if (offset == 0) + return file->f_pos; + + offset += file->f_pos; + break; + case SEEK_SET: + break; + } + + if (offset != file->f_pos) { + file->f_pos = offset; + ret = offset; + } + + return ret; +} + +static const struct file_operations adi_fops = { + .owner = THIS_MODULE, + .llseek = adi_llseek, + .read = adi_read, + .write = adi_write, + .fop_flags = FOP_UNSIGNED_OFFSET, +}; + +static struct miscdevice adi_miscdev = { + .minor = MISC_DYNAMIC_MINOR, + .name = KBUILD_MODNAME, + .fops = &adi_fops, +}; + +static int __init adi_init(void) +{ + if (!adi_capable()) + return -EPERM; + + return misc_register(&adi_miscdev); +} + +static void __exit adi_exit(void) +{ + misc_deregister(&adi_miscdev); +} + +module_init(adi_init); +module_exit(adi_exit); + +MODULE_AUTHOR("Tom Hromatka "); +MODULE_DESCRIPTION("Privileged interface to ADI"); +MODULE_VERSION("1.0"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1