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ccbcdf7cf1
The order-based approach is not only less efficient (requiring a shift and a compare, typical generated code looking like this mov eax, [machine_to_phys_order] mov ecx, eax shr ebx, cl test ebx, ebx jnz ... whereas a direct check requires just a compare, like in cmp ebx, [machine_to_phys_nr] jae ... ), but also slightly dangerous in the 32-on-64 case - the element address calculation can wrap if the next power of two boundary is sufficiently far away from the actual upper limit of the table, and hence can result in user space addresses being accessed (with it being unknown what may actually be mapped there). Additionally, the elimination of the mistaken use of fls() here (should have been __fls()) fixes a latent issue on x86-64 that would trigger if the code was run on a system with memory extending beyond the 44-bit boundary. CC: stable@kernel.org Signed-off-by: Jan Beulich <jbeulich@novell.com> [v1: Based on Jeremy's feedback] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
216 lines
6.2 KiB
C++
216 lines
6.2 KiB
C++
#ifndef _ASM_X86_XEN_PAGE_H
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#define _ASM_X86_XEN_PAGE_H
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/spinlock.h>
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#include <linux/pfn.h>
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#include <linux/mm.h>
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#include <asm/uaccess.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <xen/interface/xen.h>
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#include <xen/features.h>
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/* Xen machine address */
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typedef struct xmaddr {
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phys_addr_t maddr;
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} xmaddr_t;
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/* Xen pseudo-physical address */
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typedef struct xpaddr {
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phys_addr_t paddr;
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} xpaddr_t;
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#define XMADDR(x) ((xmaddr_t) { .maddr = (x) })
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#define XPADDR(x) ((xpaddr_t) { .paddr = (x) })
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/**** MACHINE <-> PHYSICAL CONVERSION MACROS ****/
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#define INVALID_P2M_ENTRY (~0UL)
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#define FOREIGN_FRAME_BIT (1UL<<(BITS_PER_LONG-1))
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#define IDENTITY_FRAME_BIT (1UL<<(BITS_PER_LONG-2))
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#define FOREIGN_FRAME(m) ((m) | FOREIGN_FRAME_BIT)
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#define IDENTITY_FRAME(m) ((m) | IDENTITY_FRAME_BIT)
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/* Maximum amount of memory we can handle in a domain in pages */
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#define MAX_DOMAIN_PAGES \
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((unsigned long)((u64)CONFIG_XEN_MAX_DOMAIN_MEMORY * 1024 * 1024 * 1024 / PAGE_SIZE))
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extern unsigned long *machine_to_phys_mapping;
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extern unsigned long machine_to_phys_nr;
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extern unsigned long get_phys_to_machine(unsigned long pfn);
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extern bool set_phys_to_machine(unsigned long pfn, unsigned long mfn);
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extern bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
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extern unsigned long set_phys_range_identity(unsigned long pfn_s,
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unsigned long pfn_e);
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extern int m2p_add_override(unsigned long mfn, struct page *page,
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bool clear_pte);
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extern int m2p_remove_override(struct page *page, bool clear_pte);
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extern struct page *m2p_find_override(unsigned long mfn);
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extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn);
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#ifdef CONFIG_XEN_DEBUG_FS
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extern int p2m_dump_show(struct seq_file *m, void *v);
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#endif
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static inline unsigned long pfn_to_mfn(unsigned long pfn)
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{
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unsigned long mfn;
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if (xen_feature(XENFEAT_auto_translated_physmap))
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return pfn;
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mfn = get_phys_to_machine(pfn);
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if (mfn != INVALID_P2M_ENTRY)
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mfn &= ~(FOREIGN_FRAME_BIT | IDENTITY_FRAME_BIT);
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return mfn;
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}
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static inline int phys_to_machine_mapping_valid(unsigned long pfn)
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{
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if (xen_feature(XENFEAT_auto_translated_physmap))
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return 1;
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return get_phys_to_machine(pfn) != INVALID_P2M_ENTRY;
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}
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static inline unsigned long mfn_to_pfn(unsigned long mfn)
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{
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unsigned long pfn;
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int ret = 0;
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if (xen_feature(XENFEAT_auto_translated_physmap))
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return mfn;
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if (unlikely(mfn >= machine_to_phys_nr)) {
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pfn = ~0;
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goto try_override;
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}
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pfn = 0;
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/*
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* The array access can fail (e.g., device space beyond end of RAM).
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* In such cases it doesn't matter what we return (we return garbage),
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* but we must handle the fault without crashing!
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*/
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ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
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try_override:
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/* ret might be < 0 if there are no entries in the m2p for mfn */
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if (ret < 0)
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pfn = ~0;
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else if (get_phys_to_machine(pfn) != mfn)
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/*
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* If this appears to be a foreign mfn (because the pfn
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* doesn't map back to the mfn), then check the local override
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* table to see if there's a better pfn to use.
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*
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* m2p_find_override_pfn returns ~0 if it doesn't find anything.
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*/
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pfn = m2p_find_override_pfn(mfn, ~0);
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/*
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* pfn is ~0 if there are no entries in the m2p for mfn or if the
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* entry doesn't map back to the mfn and m2p_override doesn't have a
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* valid entry for it.
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*/
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if (pfn == ~0 &&
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get_phys_to_machine(mfn) == IDENTITY_FRAME(mfn))
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pfn = mfn;
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return pfn;
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}
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static inline xmaddr_t phys_to_machine(xpaddr_t phys)
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{
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unsigned offset = phys.paddr & ~PAGE_MASK;
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return XMADDR(PFN_PHYS(pfn_to_mfn(PFN_DOWN(phys.paddr))) | offset);
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}
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static inline xpaddr_t machine_to_phys(xmaddr_t machine)
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{
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unsigned offset = machine.maddr & ~PAGE_MASK;
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return XPADDR(PFN_PHYS(mfn_to_pfn(PFN_DOWN(machine.maddr))) | offset);
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}
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/*
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* We detect special mappings in one of two ways:
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* 1. If the MFN is an I/O page then Xen will set the m2p entry
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* to be outside our maximum possible pseudophys range.
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* 2. If the MFN belongs to a different domain then we will certainly
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* not have MFN in our p2m table. Conversely, if the page is ours,
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* then we'll have p2m(m2p(MFN))==MFN.
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* If we detect a special mapping then it doesn't have a 'struct page'.
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* We force !pfn_valid() by returning an out-of-range pointer.
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*
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* NB. These checks require that, for any MFN that is not in our reservation,
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* there is no PFN such that p2m(PFN) == MFN. Otherwise we can get confused if
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* we are foreign-mapping the MFN, and the other domain as m2p(MFN) == PFN.
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* Yikes! Various places must poke in INVALID_P2M_ENTRY for safety.
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*
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* NB2. When deliberately mapping foreign pages into the p2m table, you *must*
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* use FOREIGN_FRAME(). This will cause pte_pfn() to choke on it, as we
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* require. In all the cases we care about, the FOREIGN_FRAME bit is
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* masked (e.g., pfn_to_mfn()) so behaviour there is correct.
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*/
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static inline unsigned long mfn_to_local_pfn(unsigned long mfn)
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{
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unsigned long pfn = mfn_to_pfn(mfn);
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if (get_phys_to_machine(pfn) != mfn)
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return -1; /* force !pfn_valid() */
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return pfn;
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}
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/* VIRT <-> MACHINE conversion */
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#define virt_to_machine(v) (phys_to_machine(XPADDR(__pa(v))))
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#define virt_to_pfn(v) (PFN_DOWN(__pa(v)))
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#define virt_to_mfn(v) (pfn_to_mfn(virt_to_pfn(v)))
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#define mfn_to_virt(m) (__va(mfn_to_pfn(m) << PAGE_SHIFT))
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static inline unsigned long pte_mfn(pte_t pte)
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{
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return (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT;
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}
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static inline pte_t mfn_pte(unsigned long page_nr, pgprot_t pgprot)
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{
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pte_t pte;
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pte.pte = ((phys_addr_t)page_nr << PAGE_SHIFT) |
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massage_pgprot(pgprot);
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return pte;
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}
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static inline pteval_t pte_val_ma(pte_t pte)
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{
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return pte.pte;
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}
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static inline pte_t __pte_ma(pteval_t x)
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{
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return (pte_t) { .pte = x };
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}
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#define pmd_val_ma(v) ((v).pmd)
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#ifdef __PAGETABLE_PUD_FOLDED
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#define pud_val_ma(v) ((v).pgd.pgd)
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#else
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#define pud_val_ma(v) ((v).pud)
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#endif
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#define __pmd_ma(x) ((pmd_t) { (x) } )
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#define pgd_val_ma(x) ((x).pgd)
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void xen_set_domain_pte(pte_t *ptep, pte_t pteval, unsigned domid);
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xmaddr_t arbitrary_virt_to_machine(void *address);
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unsigned long arbitrary_virt_to_mfn(void *vaddr);
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void make_lowmem_page_readonly(void *vaddr);
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void make_lowmem_page_readwrite(void *vaddr);
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#endif /* _ASM_X86_XEN_PAGE_H */
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