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| author | Juergen Gross <jgross@suse.com> | 2014-11-28 10:53:59 (GMT) |
|---|---|---|
| committer | David Vrabel <david.vrabel@citrix.com> | 2014-12-04 14:09:20 (GMT) |
| commit | 2e917175e1ef147a527a9158b9f09773ec94c0bd (patch) | |
| tree | 0e2d5e5f1cdd88bc459e284eb9dc88c1c1b6e7bc | |
| parent | 054954eb051f35e74b75a566a96fe756015352c8 (diff) | |
| download | linux-2e917175e1ef147a527a9158b9f09773ec94c0bd.tar.xz | |
xen: Speed up set_phys_to_machine() by using read-only mappings
Instead of checking at each call of set_phys_to_machine() whether a
new p2m page has to be allocated due to writing an entry in a large
invalid or identity area, just map those areas read only and react
to a page fault on write by allocating the new page.
This change will make the common path with no allocation much
faster as it only requires a single write of the new mfn instead
of walking the address translation tables and checking for the
special cases.
Suggested-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
| -rw-r--r-- | arch/x86/xen/p2m.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 7d84473..8b5db51 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -70,6 +70,7 @@ #include <asm/cache.h> #include <asm/setup.h> +#include <asm/uaccess.h> #include <asm/xen/page.h> #include <asm/xen/hypercall.h> @@ -316,9 +317,9 @@ static void __init xen_rebuild_p2m_list(unsigned long *p2m) paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT); for (i = 0; i < PTRS_PER_PTE; i++) { set_pte(p2m_missing_pte + i, - pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL)); + pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO)); set_pte(p2m_identity_pte + i, - pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL)); + pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO)); } for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) { @@ -365,7 +366,7 @@ static void __init xen_rebuild_p2m_list(unsigned long *p2m) p2m_missing : p2m_identity; ptep = populate_extra_pte((unsigned long)(p2m + pfn)); set_pte(ptep, - pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL)); + pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO)); continue; } @@ -624,6 +625,9 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) return true; } + if (likely(!__put_user(mfn, xen_p2m_addr + pfn))) + return true; + ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level); BUG_ON(!ptep || level != PG_LEVEL_4K); @@ -633,9 +637,7 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity))) return mfn == IDENTITY_FRAME(pfn); - xen_p2m_addr[pfn] = mfn; - - return true; + return false; } bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) |