On Wed, Apr 03, 2019 at 11:34:05AM -0600, Khalid Aziz wrote:
> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
> index 2779ace16d23..5c0e1581fa56 100644
> --- a/arch/x86/include/asm/pgtable.h
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -1437,6 +1437,32 @@ static inline bool arch_has_pfn_modify_check(void)
> return boot_cpu_has_bug(X86_BUG_L1TF);
> }
>
> +/*
> + * The current flushing context - we pass it instead of 5 arguments:
> + */
> +struct cpa_data {
> + unsigned long *vaddr;
> + pgd_t *pgd;
> + pgprot_t mask_set;
> + pgprot_t mask_clr;
> + unsigned long numpages;
> + unsigned long curpage;
> + unsigned long pfn;
> + unsigned int flags;
> + unsigned int force_split : 1,
> + force_static_prot : 1;
> + struct page **pages;
> +};
> +
> +
> +int
> +should_split_large_page(pte_t *kpte, unsigned long address,
> + struct cpa_data *cpa);
> +extern spinlock_t cpa_lock;
> +int
> +__split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
> + struct page *base);
> +
I really hate exposing all that.
> #include <asm-generic/pgtable.h>
> #endif /* __ASSEMBLY__ */
>
> diff --git a/arch/x86/mm/xpfo.c b/arch/x86/mm/xpfo.c
> new file mode 100644
> index 000000000000..3045bb7e4659
> --- /dev/null
> +++ b/arch/x86/mm/xpfo.c
> @@ -0,0 +1,123 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2017 Hewlett Packard Enterprise Development, L.P.
> + * Copyright (C) 2016 Brown University. All rights reserved.
> + *
> + * Authors:
> + * Juerg Haefliger <juerg.haefli...@hpe.com>
> + * Vasileios P. Kemerlis <v...@cs.brown.edu>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published
> by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/mm.h>
> +
> +#include <asm/tlbflush.h>
> +
> +extern spinlock_t cpa_lock;
> +
> +/* Update a single kernel page table entry */
> +inline void set_kpte(void *kaddr, struct page *page, pgprot_t prot)
> +{
> + unsigned int level;
> + pgprot_t msk_clr;
> + pte_t *pte = lookup_address((unsigned long)kaddr, &level);
> +
> + if (unlikely(!pte)) {
> + WARN(1, "xpfo: invalid address %p\n", kaddr);
> + return;
> + }
> +
> + switch (level) {
> + case PG_LEVEL_4K:
> + set_pte_atomic(pte, pfn_pte(page_to_pfn(page),
> + canon_pgprot(prot)));
(sorry, do we also need a nikon_pgprot() ? :-)
> + break;
> + case PG_LEVEL_2M:
> + case PG_LEVEL_1G: {
> + struct cpa_data cpa = { };
> + int do_split;
> +
> + if (level == PG_LEVEL_2M)
> + msk_clr = pmd_pgprot(*(pmd_t *)pte);
> + else
> + msk_clr = pud_pgprot(*(pud_t *)pte);
> +
> + cpa.vaddr = kaddr;
> + cpa.pages = &page;
> + cpa.mask_set = prot;
> + cpa.mask_clr = msk_clr;
> + cpa.numpages = 1;
> + cpa.flags = 0;
> + cpa.curpage = 0;
> + cpa.force_split = 0;
> +
> +
> + do_split = should_split_large_page(pte, (unsigned long)kaddr,
> + &cpa);
> + if (do_split) {
> + struct page *base;
> +
> + base = alloc_pages(GFP_ATOMIC, 0);
> + if (!base) {
> + WARN(1, "xpfo: failed to split large page\n");
You have to be fcking kidding right? A WARN when a GFP_ATOMIC allocation
fails?!
> + break;
> + }
> +
> + if (!debug_pagealloc_enabled())
> + spin_lock(&cpa_lock);
> + if (__split_large_page(&cpa, pte, (unsigned long)kaddr,
> + base) < 0) {
> + __free_page(base);
> + WARN(1, "xpfo: failed to split large page\n");
> + }
> + if (!debug_pagealloc_enabled())
> + spin_unlock(&cpa_lock);
> + }
> +
> + break;
Ever heard of helper functions?
> + }
> + case PG_LEVEL_512G:
> + /* fallthrough, splitting infrastructure doesn't
> + * support 512G pages.
> + */
Broken coment style.
> + default:
> + WARN(1, "xpfo: unsupported page level %x\n", level);
> + }
> +
> +}
> +EXPORT_SYMBOL_GPL(set_kpte);
> +
> +inline void xpfo_flush_kernel_tlb(struct page *page, int order)
> +{
> + int level;
> + unsigned long size, kaddr;
> +
> + kaddr = (unsigned long)page_address(page);
> +
> + if (unlikely(!lookup_address(kaddr, &level))) {
> + WARN(1, "xpfo: invalid address to flush %lx %d\n", kaddr,
> + level);
> + return;
> + }
> +
> + switch (level) {
> + case PG_LEVEL_4K:
> + size = PAGE_SIZE;
> + break;
> + case PG_LEVEL_2M:
> + size = PMD_SIZE;
> + break;
> + case PG_LEVEL_1G:
> + size = PUD_SIZE;
> + break;
> + default:
> + WARN(1, "xpfo: unsupported page level %x\n", level);
> + return;
> + }
> +
> + flush_tlb_kernel_range(kaddr, kaddr + (1 << order) * size);
> +}
You call this from IRQ/IRQ-disabled context... that _CANNOT_ be right.
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