path: root/arch/i386/xen/enlighten.c
diff options
authorJeremy Fitzhardinge <jeremy@xensource.com>2007-07-17 18:37:04 -0700
committerJeremy Fitzhardinge <jeremy@goop.org>2007-07-18 08:47:42 -0700
commit3b827c1b3aadf3adb4c602d19863f2d24e7cbc18 (patch)
treec889f2e3023102be09173d53dd3620567c9e6fe3 /arch/i386/xen/enlighten.c
parent5ead97c84fa7d63a6a7a2f4e9f18f452bd109045 (diff)
xen: virtual mmu
Xen pagetable handling, including the machinery to implement direct pagetables. Xen presents the real CPU's pagetables directly to guests, with no added shadowing or other layer of abstraction. Naturally this means the hypervisor must maintain close control over what the guest can put into the pagetable. When the guest modifies the pte/pmd/pgd, it must convert its domain-specific notion of a "physical" pfn into a global machine frame number (mfn) before inserting the entry into the pagetable. Xen will check to make sure the domain is allowed to create a mapping of the given mfn. Xen also requires that all mappings the guest has of its own active pagetable are read-only. This is relatively easy to implement in Linux because all pagetables share the same pte pages for kernel mappings, so updating the pte in one pagetable will implicitly update the mapping in all pagetables. Normally a pagetable becomes active when you point to it with cr3 (or the Xen equivalent), but when you do so, Xen must check the whole pagetable for correctness, which is clearly a performance problem. Xen solves this with pinning which keeps a pagetable effectively active even if its currently unused, which means that all the normal update rules are enforced. This means that it need not revalidate the pagetable when loading cr3. This patch has a first-cut implementation of pinning, but it is more fully implemented in a later patch. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Diffstat (limited to 'arch/i386/xen/enlighten.c')
1 files changed, 26 insertions, 4 deletions
diff --git a/arch/i386/xen/enlighten.c b/arch/i386/xen/enlighten.c
index 2d484f9320de..c0b0aa7af145 100644
--- a/arch/i386/xen/enlighten.c
+++ b/arch/i386/xen/enlighten.c
@@ -39,6 +39,7 @@
#include <asm/pgtable.h>
#include "xen-ops.h"
+#include "mmu.h"
#include "multicalls.h"
@@ -579,11 +580,9 @@ static __init void xen_pagetable_setup_done(pgd_t *base)
* Should be set_fixmap(), but shared_info is a machine
* address with no corresponding pseudo-phys address.
-#if 0
HYPERVISOR_shared_info =
(struct shared_info *)fix_to_virt(FIX_PARAVIRT_BOOTMAP);
@@ -592,9 +591,7 @@ static __init void xen_pagetable_setup_done(pgd_t *base)
HYPERVISOR_shared_info =
(struct shared_info *)__va(xen_start_info->shared_info);
-#if 0
@@ -690,6 +687,31 @@ static const struct paravirt_ops xen_paravirt_ops __initdata = {
.release_pd = xen_release_pd,
.release_pt = xen_release_pt,
+ .set_pte = xen_set_pte,
+ .set_pte_at = xen_set_pte_at,
+ .set_pmd = xen_set_pmd,
+ .pte_val = xen_pte_val,
+ .pgd_val = xen_pgd_val,
+ .make_pte = xen_make_pte,
+ .make_pgd = xen_make_pgd,
+#ifdef CONFIG_X86_PAE
+ .set_pte_atomic = xen_set_pte_atomic,
+ .set_pte_present = xen_set_pte_at,
+ .set_pud = xen_set_pud,
+ .pte_clear = xen_pte_clear,
+ .pmd_clear = xen_pmd_clear,
+ .make_pmd = xen_make_pmd,
+ .pmd_val = xen_pmd_val,
+#endif /* PAE */
+ .activate_mm = xen_activate_mm,
+ .dup_mmap = xen_dup_mmap,
+ .exit_mmap = xen_exit_mmap,
.set_lazy_mode = xen_set_lazy_mode,

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