| Message ID | 5e135be6b8754ddfa24560eec8c5d1254dba34ae.1569489002.git.hongyax@amazon.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Remove direct map from Xen | expand |
On Thu, Sep 26, 2019 at 10:46:38AM +0100, hongyax@amazon.com wrote: > From: Hongyan Xia <hongyax@amazon.com> > > Signed-off-by: Hongyan Xia <hongyax@amazon.com> > --- > xen/arch/x86/mm.c | 36 ++++++++++++++++++++++++++++++++++-- > 1 file changed, 34 insertions(+), 2 deletions(-) > > diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c > index ab760ecc1f..39ba9f9bf4 100644 > --- a/xen/arch/x86/mm.c > +++ b/xen/arch/x86/mm.c > @@ -5058,8 +5058,40 @@ l1_pgentry_t *virt_to_xen_l1e(unsigned long v) > > unsigned long virt_to_mfn_walk(void *va) > { > - l1_pgentry_t *pl1e = virt_to_xen_l1e((unsigned long)(va)); > - unsigned long ret = l1e_get_pfn(*pl1e); > + unsigned long ret; > + l3_pgentry_t *pl3e; > + l2_pgentry_t *pl2e; > + l1_pgentry_t *pl1e; > + > + /* > + * FIXME: This is rather unoptimised, because e.g. virt_to_xen_l2e > + * recomputes virt_to_xen_l3e again. Clearly one can keep the result and > + * carry on. > + */ > + > + pl3e = virt_to_xen_l3e((unsigned long)(va)); > + BUG_ON(!(l3e_get_flags(*pl3e) & _PAGE_PRESENT)); > + if ( l3e_get_flags(*pl3e) & _PAGE_PSE ) > + { > + ret = l3e_get_pfn(*pl3e); > + ret |= (((unsigned long)va & ((1UL << L3_PAGETABLE_SHIFT)-1)) >> PAGE_SHIFT); > + unmap_xen_pagetable(pl3e); > + return ret; > + } > + > + pl2e = virt_to_xen_l2e((unsigned long)(va)); > + BUG_ON(!(l2e_get_flags(*pl2e) & _PAGE_PRESENT)); > + if ( l2e_get_flags(*pl2e) & _PAGE_PSE ) > + { > + ret = l2e_get_pfn(*pl2e); > + ret |= (((unsigned long)va & ((1UL << L2_PAGETABLE_SHIFT)-1)) >> PAGE_SHIFT); > + unmap_xen_pagetable(pl2e); > + return ret; > + } > + > + pl1e = virt_to_xen_l1e((unsigned long)(va)); > + BUG_ON(!(l1e_get_flags(*pl1e) & _PAGE_PRESENT)); > + ret = l1e_get_pfn(*pl1e); Don't you end up leaking pl3e and pl2e in the !PSE case? Also, if you only want to walk page table that is already populated, there may be a better way to do it than calling virt_to_xen_lXe. Wei. > unmap_xen_pagetable(pl1e); > return ret; > } > -- > 2.17.1 > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xenproject.org > https://lists.xenproject.org/mailman/listinfo/xen-devel
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index ab760ecc1f..39ba9f9bf4 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -5058,8 +5058,40 @@ l1_pgentry_t *virt_to_xen_l1e(unsigned long v) unsigned long virt_to_mfn_walk(void *va) { - l1_pgentry_t *pl1e = virt_to_xen_l1e((unsigned long)(va)); - unsigned long ret = l1e_get_pfn(*pl1e); + unsigned long ret; + l3_pgentry_t *pl3e; + l2_pgentry_t *pl2e; + l1_pgentry_t *pl1e; + + /* + * FIXME: This is rather unoptimised, because e.g. virt_to_xen_l2e + * recomputes virt_to_xen_l3e again. Clearly one can keep the result and + * carry on. + */ + + pl3e = virt_to_xen_l3e((unsigned long)(va)); + BUG_ON(!(l3e_get_flags(*pl3e) & _PAGE_PRESENT)); + if ( l3e_get_flags(*pl3e) & _PAGE_PSE ) + { + ret = l3e_get_pfn(*pl3e); + ret |= (((unsigned long)va & ((1UL << L3_PAGETABLE_SHIFT)-1)) >> PAGE_SHIFT); + unmap_xen_pagetable(pl3e); + return ret; + } + + pl2e = virt_to_xen_l2e((unsigned long)(va)); + BUG_ON(!(l2e_get_flags(*pl2e) & _PAGE_PRESENT)); + if ( l2e_get_flags(*pl2e) & _PAGE_PSE ) + { + ret = l2e_get_pfn(*pl2e); + ret |= (((unsigned long)va & ((1UL << L2_PAGETABLE_SHIFT)-1)) >> PAGE_SHIFT); + unmap_xen_pagetable(pl2e); + return ret; + } + + pl1e = virt_to_xen_l1e((unsigned long)(va)); + BUG_ON(!(l1e_get_flags(*pl1e) & _PAGE_PRESENT)); + ret = l1e_get_pfn(*pl1e); unmap_xen_pagetable(pl1e); return ret; }