From: George Dunlap <george.dunlap@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Xen-devel <xen-devel@lists.xen.org>
Cc: George Dunlap <george.dunlap@eu.citrix.com>,
Jan Beulich <JBeulich@suse.com>
Subject: Re: [PATCH v7.1 07/24] x86/mm: Introduce modify_xen_mappings()
Date: Mon, 11 Apr 2016 16:21:18 +0100 [thread overview]
Message-ID: <570BC0EE.8070100@citrix.com> (raw)
In-Reply-To: <1460383444-4492-1-git-send-email-andrew.cooper3@citrix.com>
On 11/04/16 15:04, Andrew Cooper wrote:
> To simply change the permissions on existing Xen mappings. The existing
> destroy_xen_mappings() is altered to support a change the PTE permissions.
>
> A new destroy_xen_mappings() is introduced, as the special case of not passing
> _PAGE_PRESENT to modify_xen_mappings().
>
> As cleanup (and an ideal functional test), the boot logic which remaps Xen's
> code and data with reduced permissions is altered to use
> modify_xen_mappings(), rather than map_pages_to_xen() passing the same mfn's
> back in.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Looks good to me, thanks:
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: George Dunlap <george.dunlap@eu.citrix.com>
>
> Changes:
> * Allow callers to pass PAGE_HYPERVISOR_xxx constants, for consistently with
> similar functions.
> * Replace one opencoded 0 with its logical equivalent, _PAGE_NONE.
> ---
> xen/arch/x86/mm.c | 71 ++++++++++++++++++++++++++++++++++++++++++++--------
> xen/arch/x86/setup.c | 22 +++++++---------
> xen/include/xen/mm.h | 2 ++
> 3 files changed, 72 insertions(+), 23 deletions(-)
>
> diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
> index bca7532..dbe9c4f 100644
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -5956,7 +5956,19 @@ int populate_pt_range(unsigned long virt, unsigned long mfn,
> return map_pages_to_xen(virt, mfn, nr_mfns, MAP_SMALL_PAGES);
> }
>
> -void destroy_xen_mappings(unsigned long s, unsigned long e)
> +/*
> + * Alter the permissions of a range of Xen virtual address space.
> + *
> + * Does not create new mappings, and does not modify the mfn in existing
> + * mappings, but will shatter superpages if necessary, and will destroy
> + * mappings if not passed _PAGE_PRESENT.
> + *
> + * The only flags considered are NX, RW and PRESENT. All other input flags
> + * are ignored.
> + *
> + * It is an error to call with present flags over an unpopulated range.
> + */
> +void modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
> {
> bool_t locking = system_state > SYS_STATE_boot;
> l2_pgentry_t *pl2e;
> @@ -5964,6 +5976,10 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
> unsigned int i;
> unsigned long v = s;
>
> + /* Set of valid PTE bits which may be altered. */
> +#define FLAGS_MASK (_PAGE_NX|_PAGE_RW|_PAGE_PRESENT)
> + nf &= FLAGS_MASK;
> +
> ASSERT(IS_ALIGNED(s, PAGE_SIZE));
> ASSERT(IS_ALIGNED(e, PAGE_SIZE));
>
> @@ -5973,6 +5989,9 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
>
> if ( !(l3e_get_flags(*pl3e) & _PAGE_PRESENT) )
> {
> + /* Confirm the caller isn't trying to create new mappings. */
> + ASSERT(!(nf & _PAGE_PRESENT));
> +
> v += 1UL << L3_PAGETABLE_SHIFT;
> v &= ~((1UL << L3_PAGETABLE_SHIFT) - 1);
> continue;
> @@ -5984,8 +6003,12 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
> l1_table_offset(v) == 0 &&
> ((e - v) >= (1UL << L3_PAGETABLE_SHIFT)) )
> {
> - /* PAGE1GB: whole superpage is destroyed. */
> - l3e_write_atomic(pl3e, l3e_empty());
> + /* PAGE1GB: whole superpage is modified. */
> + l3_pgentry_t nl3e = !(nf & _PAGE_PRESENT) ? l3e_empty()
> + : l3e_from_pfn(l3e_get_pfn(*pl3e),
> + (l3e_get_flags(*pl3e) & ~FLAGS_MASK) | nf);
> +
> + l3e_write_atomic(pl3e, nl3e);
> v += 1UL << L3_PAGETABLE_SHIFT;
> continue;
> }
> @@ -6016,6 +6039,9 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
>
> if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) )
> {
> + /* Confirm the caller isn't trying to create new mappings. */
> + ASSERT(!(nf & _PAGE_PRESENT));
> +
> v += 1UL << L2_PAGETABLE_SHIFT;
> v &= ~((1UL << L2_PAGETABLE_SHIFT) - 1);
> continue;
> @@ -6026,8 +6052,12 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
> if ( (l1_table_offset(v) == 0) &&
> ((e-v) >= (1UL << L2_PAGETABLE_SHIFT)) )
> {
> - /* PSE: whole superpage is destroyed. */
> - l2e_write_atomic(pl2e, l2e_empty());
> + /* PSE: whole superpage is modified. */
> + l2_pgentry_t nl2e = !(nf & _PAGE_PRESENT) ? l2e_empty()
> + : l2e_from_pfn(l2e_get_pfn(*pl2e),
> + (l2e_get_flags(*pl2e) & ~FLAGS_MASK) | nf);
> +
> + l2e_write_atomic(pl2e, nl2e);
> v += 1UL << L2_PAGETABLE_SHIFT;
> }
> else
> @@ -6055,13 +6085,23 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
> }
> else
> {
> + l1_pgentry_t nl1e;
> +
> /* Ordinary 4kB mapping. */
> pl1e = l2e_to_l1e(*pl2e) + l1_table_offset(v);
> - l1e_write_atomic(pl1e, l1e_empty());
> +
> + nl1e = !(nf & _PAGE_PRESENT) ? l1e_empty()
> + : l1e_from_pfn(l1e_get_pfn(*pl1e),
> + (l1e_get_flags(*pl1e) & ~FLAGS_MASK) | nf);
> +
> + l1e_write_atomic(pl1e, nl1e);
> v += PAGE_SIZE;
>
> - /* If we are done with the L2E, check if it is now empty. */
> - if ( (v != e) && (l1_table_offset(v) != 0) )
> + /*
> + * If we are destroying mappings and done with the L2E, check if
> + * it is now empty.
> + */
> + if ( (nf & _PAGE_PRESENT) && (v != e) && (l1_table_offset(v) != 0) )
> continue;
> pl1e = l2e_to_l1e(*pl2e);
> for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
> @@ -6076,8 +6116,12 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
> }
> }
>
> - /* If we are done with the L3E, check if it is now empty. */
> - if ( (v != e) && (l2_table_offset(v) + l1_table_offset(v) != 0) )
> + /*
> + * If we are destroying mappings and done with the L3E, check if it is
> + * now empty.
> + */
> + if ( (nf & _PAGE_PRESENT) && (v != e) &&
> + (l2_table_offset(v) + l1_table_offset(v) != 0) )
> continue;
> pl2e = l3e_to_l2e(*pl3e);
> for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
> @@ -6093,10 +6137,17 @@ void destroy_xen_mappings(unsigned long s, unsigned long e)
> }
>
> flush_area(NULL, FLUSH_TLB_GLOBAL);
> +
> +#undef FLAGS_MASK
> }
>
> #undef flush_area
>
> +void destroy_xen_mappings(unsigned long s, unsigned long e)
> +{
> + modify_xen_mappings(s, e, _PAGE_NONE);
> +}
> +
> void __set_fixmap(
> enum fixed_addresses idx, unsigned long mfn, unsigned long flags)
> {
> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> index 3696c31..1a223d4 100644
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1214,23 +1214,19 @@ void __init noreturn __start_xen(unsigned long mbi_p)
> if ( !using_2M_mapping() )
> {
> /* Mark .text as RX (avoiding the first 2M superpage). */
> - map_pages_to_xen(XEN_VIRT_START + MB(2),
> - PFN_DOWN(__pa(XEN_VIRT_START + MB(2))),
> - PFN_DOWN(__2M_text_end -
> - (const char *)(XEN_VIRT_START + MB(2))),
> - PAGE_HYPERVISOR_RX);
> + modify_xen_mappings(XEN_VIRT_START + MB(2),
> + (unsigned long)&__2M_text_end,
> + PAGE_HYPERVISOR_RX);
>
> /* Mark .rodata as RO. */
> - map_pages_to_xen((unsigned long)&__2M_rodata_start,
> - PFN_DOWN(__pa(__2M_rodata_start)),
> - PFN_DOWN(__2M_rodata_end - __2M_rodata_start),
> - PAGE_HYPERVISOR_RO);
> + modify_xen_mappings((unsigned long)&__2M_rodata_start,
> + (unsigned long)&__2M_rodata_end,
> + PAGE_HYPERVISOR_RO);
>
> /* Mark .data and .bss as RW. */
> - map_pages_to_xen((unsigned long)&__2M_rwdata_start,
> - PFN_DOWN(__pa(__2M_rwdata_start)),
> - PFN_DOWN(__2M_rwdata_end - __2M_rwdata_start),
> - PAGE_HYPERVISOR_RW);
> + modify_xen_mappings((unsigned long)&__2M_rwdata_start,
> + (unsigned long)&__2M_rwdata_end,
> + PAGE_HYPERVISOR_RW);
>
> /* Drop the remaining mappings in the shattered superpage. */
> destroy_xen_mappings((unsigned long)&__2M_rwdata_end,
> diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
> index d62394f..d4721fc 100644
> --- a/xen/include/xen/mm.h
> +++ b/xen/include/xen/mm.h
> @@ -103,6 +103,8 @@ int map_pages_to_xen(
> unsigned long mfn,
> unsigned long nr_mfns,
> unsigned int flags);
> +/* Alter the permissions of a range of Xen virtual address space. */
> +void modify_xen_mappings(unsigned long s, unsigned long e, unsigned int flags);
> void destroy_xen_mappings(unsigned long v, unsigned long e);
> /*
> * Create only non-leaf page table entries for the
>
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next prev parent reply other threads:[~2016-04-11 15:21 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-10 21:14 [PATCH v7] xSplice v1 design and implementation Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 01/24] xsplice: Design document Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 02/24] xen/xsplice: Hypervisor implementation of XEN_XSPLICE_op Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 03/24] libxc: Implementation of XEN_XSPLICE_op in libxc Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 04/24] xen-xsplice: Tool to manipulate xsplice payloads Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 05/24] arm/x86: Use struct virtual_region to do bug, symbol, and (x86) exception tables lookup Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 06/24] arm/x86/vmap: Add vmalloc_xen, vfree_xen and vm_init_type Konrad Rzeszutek Wilk
2016-04-11 9:39 ` Andrew Cooper
2016-04-11 13:29 ` Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 07/24] x86/mm: Introduce modify_xen_mappings() Konrad Rzeszutek Wilk
2016-04-11 12:51 ` George Dunlap
2016-04-11 13:00 ` Andrew Cooper
2016-04-11 14:04 ` [PATCH v7.1 " Andrew Cooper
2016-04-11 15:21 ` George Dunlap [this message]
2016-04-11 17:18 ` Jan Beulich
2016-04-11 17:33 ` Andrew Cooper
2016-04-11 17:46 ` [PATCH v7.2 " Andrew Cooper
2016-04-11 17:54 ` Jan Beulich
2016-04-12 9:08 ` Andrew Cooper
2016-04-10 21:14 ` [PATCH v7 08/24] xsplice: Add helper elf routines Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 09/24] xsplice: Implement payload loading Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 10/24] xsplice: Implement support for applying/reverting/replacing patches Konrad Rzeszutek Wilk
2016-04-11 10:14 ` Andrew Cooper
2016-04-11 13:29 ` Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 11/24] x86/xen_hello_world.xsplice: Test payload for patching 'xen_extra_version' Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 12/24] xsplice, symbols: Implement symbol name resolution on address Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 13/24] x86, xsplice: Print payload's symbol name and payload name in backtraces Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 14/24] xsplice: Add support for bug frames Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 15/24] xsplice: Add support for exception tables Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 16/24] xsplice: Add support for alternatives Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 17/24] build_id: Provide ld-embedded build-ids Konrad Rzeszutek Wilk
2016-04-11 12:17 ` Andrew Cooper
2016-04-11 13:31 ` Konrad Rzeszutek Wilk
2016-04-11 13:35 ` Andrew Cooper
2016-04-10 21:14 ` [PATCH v7 18/24] HYPERCALL_version_op: Add VERSION_build_id to retrieve build-id Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 19/24] libxl: info: Display build_id of the hypervisor using XEN_VERSION_build_id Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 20/24] xsplice: Print build_id in keyhandler and on bootup Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 21/24] xsplice: Stacking build-id dependency checking Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 22/24] xsplice/xen_replace_world: Test-case for XSPLICE_ACTION_REPLACE Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 23/24] xsplice: Prevent duplicate payloads from being loaded Konrad Rzeszutek Wilk
2016-04-10 21:14 ` [PATCH v7 24/24] MAINTAINERS/xsplice: Add myself and Ross as the maintainers Konrad Rzeszutek Wilk
2016-04-11 14:32 ` [PATCH v7] xSplice v1 design and implementation Konrad Rzeszutek Wilk
2016-04-11 15:43 ` Konrad Rzeszutek Wilk
2016-04-12 8:10 ` Ross Lagerwall
2016-04-12 20:59 ` Konrad Rzeszutek Wilk
2016-04-12 20:59 ` [PATCH v7 25/24] symbols/xsplice: Implement fast symbol names -> virtual addresses lookup Konrad Rzeszutek Wilk
2016-04-13 2:03 ` Konrad Rzeszutek Wilk
2016-04-13 2:17 ` Konrad Rzeszutek Wilk
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