src/kernel/linux/v4.19/arch/x86/xen/mmu.c

#include <linux/pfn.h>
#include <asm/xen/page.h>
#include <asm/xen/hypercall.h>
#include <xen/interface/memory.h>

#include "multicalls.h"
#include "mmu.h"

/*
 * Protects atomic reservation decrease/increase against concurrent increases.
 * Also protects non-atomic updates of current_pages and balloon lists.
 */
DEFINE_SPINLOCK(xen_reservation_lock);

unsigned long arbitrary_virt_to_mfn(void *vaddr)
{
	xmaddr_t maddr = arbitrary_virt_to_machine(vaddr);

	return PFN_DOWN(maddr.maddr);
}

xmaddr_t arbitrary_virt_to_machine(void *vaddr)
{
	unsigned long address = (unsigned long)vaddr;
	unsigned int level;
	pte_t *pte;
	unsigned offset;

	/*
	 * if the PFN is in the linear mapped vaddr range, we can just use
	 * the (quick) virt_to_machine() p2m lookup
	 */
	if (virt_addr_valid(vaddr))
		return virt_to_machine(vaddr);

	/* otherwise we have to do a (slower) full page-table walk */

	pte = lookup_address(address, &level);
	BUG_ON(pte == NULL);
	offset = address & ~PAGE_MASK;
	return XMADDR(((phys_addr_t)pte_mfn(*pte) << PAGE_SHIFT) + offset);
}
EXPORT_SYMBOL_GPL(arbitrary_virt_to_machine);

static noinline void xen_flush_tlb_all(void)
{
	struct mmuext_op *op;
	struct multicall_space mcs;

	preempt_disable();

	mcs = xen_mc_entry(sizeof(*op));

	op = mcs.args;
	op->cmd = MMUEXT_TLB_FLUSH_ALL;
	MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);

	xen_mc_issue(PARAVIRT_LAZY_MMU);

	preempt_enable();
}

#define REMAP_BATCH_SIZE 16

struct remap_data {
	xen_pfn_t *pfn;
	bool contiguous;
	bool no_translate;
	pgprot_t prot;
	struct mmu_update *mmu_update;
};

static int remap_area_pfn_pte_fn(pte_t *ptep, pgtable_t token,
				 unsigned long addr, void *data)
{
	struct remap_data *rmd = data;
	pte_t pte = pte_mkspecial(mfn_pte(*rmd->pfn, rmd->prot));

	/*
	 * If we have a contiguous range, just update the pfn itself,
	 * else update pointer to be "next pfn".
	 */
	if (rmd->contiguous)
		(*rmd->pfn)++;
	else
		rmd->pfn++;

	rmd->mmu_update->ptr = virt_to_machine(ptep).maddr;
	rmd->mmu_update->ptr |= rmd->no_translate ?
		MMU_PT_UPDATE_NO_TRANSLATE :
		MMU_NORMAL_PT_UPDATE;
	rmd->mmu_update->val = pte_val_ma(pte);
	rmd->mmu_update++;

	return 0;
}

static int do_remap_pfn(struct vm_area_struct *vma,
			unsigned long addr,
			xen_pfn_t *pfn, int nr,
			int *err_ptr, pgprot_t prot,
			unsigned int domid,
			bool no_translate,
			struct page **pages)
{
	int err = 0;
	struct remap_data rmd;
	struct mmu_update mmu_update[REMAP_BATCH_SIZE];
	unsigned long range;
	int mapped = 0;

	BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO)));

	rmd.pfn = pfn;
	rmd.prot = prot;
	/*
	 * We use the err_ptr to indicate if there we are doing a contiguous
	 * mapping or a discontigious mapping.
	 */
	rmd.contiguous = !err_ptr;
	rmd.no_translate = no_translate;

	while (nr) {
		int index = 0;
		int done = 0;
		int batch = min(REMAP_BATCH_SIZE, nr);
		int batch_left = batch;
		range = (unsigned long)batch << PAGE_SHIFT;

		rmd.mmu_update = mmu_update;
		err = apply_to_page_range(vma->vm_mm, addr, range,
					  remap_area_pfn_pte_fn, &rmd);
		if (err)
			goto out;

		/* We record the error for each page that gives an error, but
		 * continue mapping until the whole set is done */
		do {
			int i;

			err = HYPERVISOR_mmu_update(&mmu_update[index],
						    batch_left, &done, domid);

			/*
			 * @err_ptr may be the same buffer as @gfn, so
			 * only clear it after each chunk of @gfn is
			 * used.
			 */
			if (err_ptr) {
				for (i = index; i < index + done; i++)
					err_ptr[i] = 0;
			}
			if (err < 0) {
				if (!err_ptr)
					goto out;
				err_ptr[i] = err;
				done++; /* Skip failed frame. */
			} else
				mapped += done;
			batch_left -= done;
			index += done;
		} while (batch_left);

		nr -= batch;
		addr += range;
		if (err_ptr)
			err_ptr += batch;
		cond_resched();
	}
out:

	xen_flush_tlb_all();

	return err < 0 ? err : mapped;
}

int xen_remap_domain_gfn_range(struct vm_area_struct *vma,
			       unsigned long addr,
			       xen_pfn_t gfn, int nr,
			       pgprot_t prot, unsigned domid,
			       struct page **pages)
{
	if (xen_feature(XENFEAT_auto_translated_physmap))
		return -EOPNOTSUPP;

	return do_remap_pfn(vma, addr, &gfn, nr, NULL, prot, domid, false,
			    pages);
}
EXPORT_SYMBOL_GPL(xen_remap_domain_gfn_range);

int xen_remap_domain_gfn_array(struct vm_area_struct *vma,
			       unsigned long addr,
			       xen_pfn_t *gfn, int nr,
			       int *err_ptr, pgprot_t prot,
			       unsigned domid, struct page **pages)
{
	if (xen_feature(XENFEAT_auto_translated_physmap))
		return xen_xlate_remap_gfn_array(vma, addr, gfn, nr, err_ptr,
						 prot, domid, pages);

	/* We BUG_ON because it's a programmer error to pass a NULL err_ptr,
	 * and the consequences later is quite hard to detect what the actual
	 * cause of "wrong memory was mapped in".
	 */
	BUG_ON(err_ptr == NULL);
	return do_remap_pfn(vma, addr, gfn, nr, err_ptr, prot, domid,
			    false, pages);
}
EXPORT_SYMBOL_GPL(xen_remap_domain_gfn_array);

int xen_remap_domain_mfn_array(struct vm_area_struct *vma,
			       unsigned long addr,
			       xen_pfn_t *mfn, int nr,
			       int *err_ptr, pgprot_t prot,
			       unsigned int domid, struct page **pages)
{
	if (xen_feature(XENFEAT_auto_translated_physmap))
		return -EOPNOTSUPP;

	return do_remap_pfn(vma, addr, mfn, nr, err_ptr, prot, domid,
			    true, pages);
}
EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_array);

/* Returns: 0 success */
int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
			       int nr, struct page **pages)
{
	if (xen_feature(XENFEAT_auto_translated_physmap))
		return xen_xlate_unmap_gfn_range(vma, nr, pages);

	if (!pages)
		return 0;

	return -EINVAL;
}
EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);