paging.h

xen虚拟机源代码安装包

 * Called from pagefault handler in Xen, and from the HVM trap handlers
 * for pagefaults.  Returns 1 if this fault was an artefact of the
 * paging code (and the guest should retry) or 0 if it is not (and the
 * fault should be handled elsewhere or passed to the guest).
 *
 * Note: under shadow paging, this function handles all page faults;
 * however, for hardware-assisted paging, this function handles only 
 * host page faults (i.e. nested page faults). */
static inline int
paging_fault(unsigned long va, struct cpu_user_regs *regs)
{
    struct vcpu *v = current;
    return v->arch.paging.mode->page_fault(v, va, regs);
}

/* Handle invlpg requests on vcpus.
 * Returns 1 if the invlpg instruction should be issued on the hardware,
 * or 0 if it's safe not to do so. */
static inline int paging_invlpg(struct vcpu *v, unsigned long va)
{
    return v->arch.paging.mode->invlpg(v, va);
}

/* Translate a guest virtual address to the frame number that the
 * *guest* pagetables would map it to.  Returns INVALID_GFN if the guest
 * tables don't map this address for this kind of access.
 * pfec[0] is used to determine which kind of access this is when
 * walking the tables.  The caller should set the PFEC_page_present bit
 * in pfec[0]; in the failure case, that bit will be cleared if appropriate. */
#define INVALID_GFN (-1UL)
static inline unsigned long paging_gva_to_gfn(struct vcpu *v, 
                                              unsigned long va,
                                              uint32_t *pfec)
{
    return v->arch.paging.mode->gva_to_gfn(v, va, pfec);
}

/* Update all the things that are derived from the guest's CR3.
 * Called when the guest changes CR3; the caller can then use v->arch.cr3
 * as the value to load into the host CR3 to schedule this vcpu */
static inline void paging_update_cr3(struct vcpu *v)
{
    v->arch.paging.mode->update_cr3(v, 1);
}

/* Update all the things that are derived from the guest's CR0/CR3/CR4.
 * Called to initialize paging structures if the paging mode
 * has changed, and when bringing up a VCPU for the first time. */
static inline void paging_update_paging_modes(struct vcpu *v)
{
    v->arch.paging.mode->update_paging_modes(v);
}


/* Write a new value into the guest pagetable, and update the
 * paging-assistance state appropriately.  Returns 0 if we page-faulted,
 * 1 for success. */
static inline int paging_write_guest_entry(struct vcpu *v, intpte_t *p,
                                           intpte_t new, mfn_t gmfn)
{
    if ( unlikely(paging_mode_enabled(v->domain) 
                  && v->arch.paging.mode != NULL) )
        return v->arch.paging.mode->write_guest_entry(v, p, new, gmfn);
    else 
        return (!__copy_to_user(p, &new, sizeof(new)));
}


/* Cmpxchg a new value into the guest pagetable, and update the
 * paging-assistance state appropriately.  Returns 0 if we page-faulted,
 * 1 if not.  N.B. caller should check the value of "old" to see if the
 * cmpxchg itself was successful. */
static inline int paging_cmpxchg_guest_entry(struct vcpu *v, intpte_t *p,
                                             intpte_t *old, intpte_t new, 
                                             mfn_t gmfn)
{
    if ( unlikely(paging_mode_enabled(v->domain) 
                  && v->arch.paging.mode != NULL) )
        return v->arch.paging.mode->cmpxchg_guest_entry(v, p, old, new, gmfn);
    else 
        return (!cmpxchg_user(p, *old, new));
}

/* Helper function that writes a pte in such a way that a concurrent read 
 * never sees a half-written entry that has _PAGE_PRESENT set */
static inline void safe_write_pte(l1_pgentry_t *p, l1_pgentry_t new)
{
#if CONFIG_PAGING_LEVELS == 3
    /* PAE machines write 64bit PTEs as two 32bit writes. */
    volatile unsigned long *d = (unsigned long *) p;
    unsigned long *s = (unsigned long *) &new;
    BUILD_BUG_ON(sizeof (l1_pgentry_t) != 2 * sizeof (unsigned long));
    d[0] = 0;
    d[1] = s[1];
    d[0] = s[0]; 
#else
    *p = new;
#endif
}

/* Atomically write a P2M entry and update the paging-assistance state 
 * appropriately. 
 * Arguments: the domain in question, the GFN whose mapping is being updated, 
 * a pointer to the entry to be written, the MFN in which the entry resides, 
 * the new contents of the entry, and the level in the p2m tree at which 
 * we are writing. */
static inline void paging_write_p2m_entry(struct domain *d, unsigned long gfn, 
                                          l1_pgentry_t *p, mfn_t table_mfn,
                                          l1_pgentry_t new, unsigned int level)
{
    struct vcpu *v = current;
    if ( v->domain != d )
        v = d->vcpu[0];
    if ( likely(v && paging_mode_enabled(d) && v->arch.paging.mode != NULL) )
    {
        return v->arch.paging.mode->write_p2m_entry(v, gfn, p, table_mfn,
                                                    new, level);
    }
    else 
        safe_write_pte(p, new);
}

/* Print paging-assistance info to the console */
void paging_dump_domain_info(struct domain *d);
void paging_dump_vcpu_info(struct vcpu *v);


/*****************************************************************************
 * Access to the guest pagetables */

/* Get a mapping of a PV guest's l1e for this virtual address. */
static inline void *
guest_map_l1e(struct vcpu *v, unsigned long addr, unsigned long *gl1mfn)
{
    l2_pgentry_t l2e;

    if ( unlikely(paging_mode_translate(v->domain)) )
        return v->arch.paging.mode->guest_map_l1e(v, addr, gl1mfn);

    /* Find this l1e and its enclosing l1mfn in the linear map */
    if ( __copy_from_user(&l2e, 
                          &__linear_l2_table[l2_linear_offset(addr)],
                          sizeof(l2_pgentry_t)) != 0 )
        return NULL;
    /* Check flags that it will be safe to read the l1e */
    if ( (l2e_get_flags(l2e) & (_PAGE_PRESENT | _PAGE_PSE)) 
         != _PAGE_PRESENT )
        return NULL;
    *gl1mfn = l2e_get_pfn(l2e);
    return &__linear_l1_table[l1_linear_offset(addr)];
}

/* Pull down the mapping we got from guest_map_l1e() */
static inline void
guest_unmap_l1e(struct vcpu *v, void *p)
{
    if ( unlikely(paging_mode_translate(v->domain)) )
        unmap_domain_page(p);
}

/* Read the guest's l1e that maps this address. */
static inline void
guest_get_eff_l1e(struct vcpu *v, unsigned long addr, void *eff_l1e)
{
    if ( likely(!paging_mode_translate(v->domain)) )
    {
        ASSERT(!paging_mode_external(v->domain));
        if ( __copy_from_user(eff_l1e, 
                              &__linear_l1_table[l1_linear_offset(addr)],
                              sizeof(l1_pgentry_t)) != 0 )
            *(l1_pgentry_t *)eff_l1e = l1e_empty();
        return;
    }
        
    v->arch.paging.mode->guest_get_eff_l1e(v, addr, eff_l1e);
}

/* Read the guest's l1e that maps this address, from the kernel-mode
 * pagetables. */
static inline void
guest_get_eff_kern_l1e(struct vcpu *v, unsigned long addr, void *eff_l1e)
{
#if defined(__x86_64__)
    int user_mode = !(v->arch.flags & TF_kernel_mode);
#define TOGGLE_MODE() if ( user_mode ) toggle_guest_mode(v)
#else
#define TOGGLE_MODE() ((void)0)
#endif

    TOGGLE_MODE();
    guest_get_eff_l1e(v, addr, eff_l1e);
    TOGGLE_MODE();
}



#endif /* XEN_PAGING_H */

/*
 * Local variables:
 * mode: C
 * c-set-style: "BSD"
 * c-basic-offset: 4
 * indent-tabs-mode: nil
 * End:
 */