[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] [PATCH] Optimizing x86-64 xenlinux using global pages for user mode (take 2)
Keir Fraser wrote: > On 30/8/06 7:43 am, "Nakajima, Jun" <jun.nakajima@xxxxxxxxx> wrote: > >> The previous patch had a problem with the builder, which constructs >> the initial page tables with the USER bit on. And Xen couldn't >> distinguish kernel or use pages. It was partially checked avoiding >> the bug, and it's finished with this patch. > > I'd like to avoid awareness of the extra PAGE_GUEST_KERNEL bit in > guests and tools as much as possible (in fact, entirely would be > good). The updated patch avoids that. > > There's no need for all the PAGE_KERNEL macros in Linux to include > the new flag. The absence of PAGE_USER will suffice to allow Xen to > distinguish kernel entries from user entries. All that is necessary > is for Xen to add the flag when it adds PAGE_USER to a kernel entry, > so that kernel entries remain disambiguated from user entries. > > Also, you should use one of the high-order available bits (one of bits > 52-60). Other OSes use the low-order available bits for their own > purposes -- we may as well avoid conflicting with them. > I used the bit 52 this time, but it's still possible to see such conflicts. > -- Keir arch/x86/domain_build.c | 2 +- arch/x86/flushtlb.c | 7 +++++++ arch/x86/mm.c | 29 +++++++++++++++++++++++++---- arch/x86/x86_64/traps.c | 2 +- include/asm-x86/flushtlb.h | 8 +++++++- include/asm-x86/x86_64/page.h | 7 +++++-- 6 files changed, 46 insertions(+), 9 deletions(-) Signed-off-by: Jun Nakajima <jun.nakajima@xxxxxxxxx> Jun --- Intel Open Source Technology Center Attachment:
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