cf04d120d9
In case the mfn_list does not have enough entries to fill a p2m page we do not want the entries from max_pfn up to the boundary to be filled with unknown values. Hence set them to INVALID_P2M_ENTRY. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
523 lines
13 KiB
C
523 lines
13 KiB
C
/*
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* Xen leaves the responsibility for maintaining p2m mappings to the
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* guests themselves, but it must also access and update the p2m array
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* during suspend/resume when all the pages are reallocated.
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*
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* The p2m table is logically a flat array, but we implement it as a
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* three-level tree to allow the address space to be sparse.
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*
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* Xen
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* |
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* p2m_top p2m_top_mfn
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* / \ / \
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* p2m_mid p2m_mid p2m_mid_mfn p2m_mid_mfn
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* / \ / \ / /
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* p2m p2m p2m p2m p2m p2m p2m ...
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*
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* The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
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*
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* The p2m_top and p2m_top_mfn levels are limited to 1 page, so the
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* maximum representable pseudo-physical address space is:
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* P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
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*
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* P2M_PER_PAGE depends on the architecture, as a mfn is always
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* unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
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* 512 and 1024 entries respectively.
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/list.h>
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#include <linux/hash.h>
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#include <linux/sched.h>
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#include <asm/cache.h>
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#include <asm/setup.h>
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#include <asm/xen/page.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/hypervisor.h>
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#include "xen-ops.h"
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static void __init m2p_override_init(void);
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unsigned long xen_max_p2m_pfn __read_mostly;
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#define P2M_PER_PAGE (PAGE_SIZE / sizeof(unsigned long))
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#define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *))
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#define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **))
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#define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
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/* Placeholders for holes in the address space */
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static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE);
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RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
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RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
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static inline unsigned p2m_top_index(unsigned long pfn)
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{
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BUG_ON(pfn >= MAX_P2M_PFN);
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return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
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}
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static inline unsigned p2m_mid_index(unsigned long pfn)
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{
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return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
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}
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static inline unsigned p2m_index(unsigned long pfn)
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{
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return pfn % P2M_PER_PAGE;
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}
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static void p2m_top_init(unsigned long ***top)
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{
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unsigned i;
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for (i = 0; i < P2M_TOP_PER_PAGE; i++)
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top[i] = p2m_mid_missing;
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}
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static void p2m_top_mfn_init(unsigned long *top)
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{
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unsigned i;
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for (i = 0; i < P2M_TOP_PER_PAGE; i++)
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top[i] = virt_to_mfn(p2m_mid_missing_mfn);
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}
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static void p2m_top_mfn_p_init(unsigned long **top)
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{
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unsigned i;
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for (i = 0; i < P2M_TOP_PER_PAGE; i++)
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top[i] = p2m_mid_missing_mfn;
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}
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static void p2m_mid_init(unsigned long **mid)
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{
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unsigned i;
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for (i = 0; i < P2M_MID_PER_PAGE; i++)
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mid[i] = p2m_missing;
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}
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static void p2m_mid_mfn_init(unsigned long *mid)
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{
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unsigned i;
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for (i = 0; i < P2M_MID_PER_PAGE; i++)
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mid[i] = virt_to_mfn(p2m_missing);
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}
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static void p2m_init(unsigned long *p2m)
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{
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unsigned i;
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for (i = 0; i < P2M_MID_PER_PAGE; i++)
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p2m[i] = INVALID_P2M_ENTRY;
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}
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/*
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* Build the parallel p2m_top_mfn and p2m_mid_mfn structures
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*
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* This is called both at boot time, and after resuming from suspend:
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* - At boot time we're called very early, and must use extend_brk()
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* to allocate memory.
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*
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* - After resume we're called from within stop_machine, but the mfn
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* tree should alreay be completely allocated.
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*/
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void xen_build_mfn_list_list(void)
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{
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unsigned long pfn;
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/* Pre-initialize p2m_top_mfn to be completely missing */
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if (p2m_top_mfn == NULL) {
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p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_mid_mfn_init(p2m_mid_missing_mfn);
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p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_top_mfn_p_init(p2m_top_mfn_p);
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p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_top_mfn_init(p2m_top_mfn);
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} else {
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/* Reinitialise, mfn's all change after migration */
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p2m_mid_mfn_init(p2m_mid_missing_mfn);
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}
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for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
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unsigned topidx = p2m_top_index(pfn);
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unsigned mididx = p2m_mid_index(pfn);
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unsigned long **mid;
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unsigned long *mid_mfn_p;
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mid = p2m_top[topidx];
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mid_mfn_p = p2m_top_mfn_p[topidx];
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/* Don't bother allocating any mfn mid levels if
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* they're just missing, just update the stored mfn,
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* since all could have changed over a migrate.
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*/
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if (mid == p2m_mid_missing) {
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BUG_ON(mididx);
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BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
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p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
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pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
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continue;
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}
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if (mid_mfn_p == p2m_mid_missing_mfn) {
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/*
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* XXX boot-time only! We should never find
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* missing parts of the mfn tree after
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* runtime. extend_brk() will BUG if we call
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* it too late.
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*/
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mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_mid_mfn_init(mid_mfn_p);
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p2m_top_mfn_p[topidx] = mid_mfn_p;
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}
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p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
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mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]);
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}
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}
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void xen_setup_mfn_list_list(void)
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{
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BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
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HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
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virt_to_mfn(p2m_top_mfn);
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HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
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}
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/* Set up p2m_top to point to the domain-builder provided p2m pages */
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void __init xen_build_dynamic_phys_to_machine(void)
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{
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unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
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unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
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unsigned long pfn;
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xen_max_p2m_pfn = max_pfn;
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p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_init(p2m_missing);
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p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_mid_init(p2m_mid_missing);
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p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_top_init(p2m_top);
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/*
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* The domain builder gives us a pre-constructed p2m array in
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* mfn_list for all the pages initially given to us, so we just
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* need to graft that into our tree structure.
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*/
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for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) {
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unsigned topidx = p2m_top_index(pfn);
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unsigned mididx = p2m_mid_index(pfn);
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if (p2m_top[topidx] == p2m_mid_missing) {
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unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
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p2m_mid_init(mid);
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p2m_top[topidx] = mid;
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}
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/*
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* As long as the mfn_list has enough entries to completely
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* fill a p2m page, pointing into the array is ok. But if
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* not the entries beyond the last pfn will be undefined.
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*/
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if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) {
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unsigned long p2midx;
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p2midx = max_pfn % P2M_PER_PAGE;
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for ( ; p2midx < P2M_PER_PAGE; p2midx++)
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mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY;
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}
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p2m_top[topidx][mididx] = &mfn_list[pfn];
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}
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m2p_override_init();
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}
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unsigned long get_phys_to_machine(unsigned long pfn)
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{
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unsigned topidx, mididx, idx;
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if (unlikely(pfn >= MAX_P2M_PFN))
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return INVALID_P2M_ENTRY;
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topidx = p2m_top_index(pfn);
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mididx = p2m_mid_index(pfn);
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idx = p2m_index(pfn);
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return p2m_top[topidx][mididx][idx];
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}
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EXPORT_SYMBOL_GPL(get_phys_to_machine);
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static void *alloc_p2m_page(void)
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{
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return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
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}
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static void free_p2m_page(void *p)
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{
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free_page((unsigned long)p);
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}
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/*
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* Fully allocate the p2m structure for a given pfn. We need to check
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* that both the top and mid levels are allocated, and make sure the
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* parallel mfn tree is kept in sync. We may race with other cpus, so
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* the new pages are installed with cmpxchg; if we lose the race then
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* simply free the page we allocated and use the one that's there.
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*/
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static bool alloc_p2m(unsigned long pfn)
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{
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unsigned topidx, mididx;
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unsigned long ***top_p, **mid;
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unsigned long *top_mfn_p, *mid_mfn;
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topidx = p2m_top_index(pfn);
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mididx = p2m_mid_index(pfn);
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top_p = &p2m_top[topidx];
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mid = *top_p;
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if (mid == p2m_mid_missing) {
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/* Mid level is missing, allocate a new one */
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mid = alloc_p2m_page();
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if (!mid)
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return false;
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p2m_mid_init(mid);
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if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
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free_p2m_page(mid);
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}
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top_mfn_p = &p2m_top_mfn[topidx];
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mid_mfn = p2m_top_mfn_p[topidx];
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BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
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if (mid_mfn == p2m_mid_missing_mfn) {
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/* Separately check the mid mfn level */
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unsigned long missing_mfn;
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unsigned long mid_mfn_mfn;
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mid_mfn = alloc_p2m_page();
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if (!mid_mfn)
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return false;
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p2m_mid_mfn_init(mid_mfn);
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missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
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mid_mfn_mfn = virt_to_mfn(mid_mfn);
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if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
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free_p2m_page(mid_mfn);
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else
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p2m_top_mfn_p[topidx] = mid_mfn;
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}
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if (p2m_top[topidx][mididx] == p2m_missing) {
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/* p2m leaf page is missing */
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unsigned long *p2m;
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p2m = alloc_p2m_page();
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if (!p2m)
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return false;
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p2m_init(p2m);
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if (cmpxchg(&mid[mididx], p2m_missing, p2m) != p2m_missing)
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free_p2m_page(p2m);
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else
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mid_mfn[mididx] = virt_to_mfn(p2m);
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}
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return true;
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}
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/* Try to install p2m mapping; fail if intermediate bits missing */
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bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
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{
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unsigned topidx, mididx, idx;
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if (unlikely(pfn >= MAX_P2M_PFN)) {
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BUG_ON(mfn != INVALID_P2M_ENTRY);
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return true;
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}
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topidx = p2m_top_index(pfn);
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mididx = p2m_mid_index(pfn);
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idx = p2m_index(pfn);
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if (p2m_top[topidx][mididx] == p2m_missing)
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return mfn == INVALID_P2M_ENTRY;
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p2m_top[topidx][mididx][idx] = mfn;
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return true;
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}
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bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
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{
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if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
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BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
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return true;
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}
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if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
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if (!alloc_p2m(pfn))
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return false;
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if (!__set_phys_to_machine(pfn, mfn))
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return false;
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}
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return true;
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}
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#define M2P_OVERRIDE_HASH_SHIFT 10
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#define M2P_OVERRIDE_HASH (1 << M2P_OVERRIDE_HASH_SHIFT)
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static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH);
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static DEFINE_SPINLOCK(m2p_override_lock);
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static void __init m2p_override_init(void)
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{
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unsigned i;
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m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
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sizeof(unsigned long));
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for (i = 0; i < M2P_OVERRIDE_HASH; i++)
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INIT_LIST_HEAD(&m2p_overrides[i]);
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}
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static unsigned long mfn_hash(unsigned long mfn)
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{
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return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
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}
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/* Add an MFN override for a particular page */
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int m2p_add_override(unsigned long mfn, struct page *page)
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{
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unsigned long flags;
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unsigned long pfn;
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unsigned long address;
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unsigned level;
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pte_t *ptep = NULL;
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pfn = page_to_pfn(page);
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if (!PageHighMem(page)) {
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address = (unsigned long)__va(pfn << PAGE_SHIFT);
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ptep = lookup_address(address, &level);
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if (WARN(ptep == NULL || level != PG_LEVEL_4K,
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"m2p_add_override: pfn %lx not mapped", pfn))
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return -EINVAL;
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}
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page->private = mfn;
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page->index = pfn_to_mfn(pfn);
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__set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
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if (!PageHighMem(page))
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/* Just zap old mapping for now */
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pte_clear(&init_mm, address, ptep);
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spin_lock_irqsave(&m2p_override_lock, flags);
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list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
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spin_unlock_irqrestore(&m2p_override_lock, flags);
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return 0;
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}
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int m2p_remove_override(struct page *page)
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{
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unsigned long flags;
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unsigned long mfn;
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unsigned long pfn;
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unsigned long address;
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unsigned level;
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pte_t *ptep = NULL;
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pfn = page_to_pfn(page);
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mfn = get_phys_to_machine(pfn);
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if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
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return -EINVAL;
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if (!PageHighMem(page)) {
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address = (unsigned long)__va(pfn << PAGE_SHIFT);
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ptep = lookup_address(address, &level);
|
|
|
|
if (WARN(ptep == NULL || level != PG_LEVEL_4K,
|
|
"m2p_remove_override: pfn %lx not mapped", pfn))
|
|
return -EINVAL;
|
|
}
|
|
|
|
spin_lock_irqsave(&m2p_override_lock, flags);
|
|
list_del(&page->lru);
|
|
spin_unlock_irqrestore(&m2p_override_lock, flags);
|
|
__set_phys_to_machine(pfn, page->index);
|
|
|
|
if (!PageHighMem(page))
|
|
set_pte_at(&init_mm, address, ptep,
|
|
pfn_pte(pfn, PAGE_KERNEL));
|
|
/* No tlb flush necessary because the caller already
|
|
* left the pte unmapped. */
|
|
|
|
return 0;
|
|
}
|
|
|
|
struct page *m2p_find_override(unsigned long mfn)
|
|
{
|
|
unsigned long flags;
|
|
struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
|
|
struct page *p, *ret;
|
|
|
|
ret = NULL;
|
|
|
|
spin_lock_irqsave(&m2p_override_lock, flags);
|
|
|
|
list_for_each_entry(p, bucket, lru) {
|
|
if (p->private == mfn) {
|
|
ret = p;
|
|
break;
|
|
}
|
|
}
|
|
|
|
spin_unlock_irqrestore(&m2p_override_lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
|
|
unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
|
|
{
|
|
struct page *p = m2p_find_override(mfn);
|
|
unsigned long ret = pfn;
|
|
|
|
if (p)
|
|
ret = page_to_pfn(p);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
|