diff mbox series

[v2,3/4] mini-os: fix number of pages for PVH

Message ID 20220619065253.19503-4-jgross@suse.com (mailing list archive)
State Superseded
Headers show
Series mini-os: some memory map updates for PVH | expand

Commit Message

Jürgen Groß June 19, 2022, 6:52 a.m. UTC
When getting the current allocation from Xen, this value includes the
pages allocated in the MMIO area. Fix the highest available RAM page
by subtracting the size of that area.

This requires to read the E820 map before needing this value. Add two
functions returning the current and the maximum number of RAM pages
taking this correction into account.

At the same time add the LAPIC page to the memory map in order to
avoid reusing that PFN for internal purposes.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- make e820_initial_reserved_pfns static (Samuel Thibault)
- add e820_get_current_pages() and e820_get_max_pages()
---
 arch/x86/mm.c         | 17 +++++--------
 balloon.c             | 16 +++---------
 e820.c                | 58 +++++++++++++++++++++++++++++++++++++------
 include/e820.h        |  2 ++
 include/x86/arch_mm.h |  2 ++
 5 files changed, 65 insertions(+), 30 deletions(-)

Comments

Samuel Thibault June 20, 2022, 10:43 p.m. UTC | #1
Juergen Gross, le dim. 19 juin 2022 08:52:52 +0200, a ecrit:
> When getting the current allocation from Xen, this value includes the
> pages allocated in the MMIO area. Fix the highest available RAM page
> by subtracting the size of that area.
> 
> This requires to read the E820 map before needing this value. Add two
> functions returning the current and the maximum number of RAM pages
> taking this correction into account.
> 
> At the same time add the LAPIC page to the memory map in order to
> avoid reusing that PFN for internal purposes.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> V2:
> - make e820_initial_reserved_pfns static (Samuel Thibault)
> - add e820_get_current_pages() and e820_get_max_pages()
> ---

> diff --git a/include/e820.h b/include/e820.h
> index 5438a7c8..6f15fcd2 100644
> --- a/include/e820.h
> +++ b/include/e820.h
> @@ -52,6 +52,8 @@ struct __packed e820entry {
>  extern struct e820entry e820_map[];
>  extern unsigned e820_entries;
>  
> +unsigned int e820_get_current_pages(void);
> +unsigned int e820_get_max_pages(void);

Why an int rather than a long int? Yes 4TiB memory is large for mini-os,
but better keep numbers of pages a long?

Apart from that,

Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

Samuel
Jürgen Groß June 21, 2022, 7:18 a.m. UTC | #2
On 21.06.22 00:43, Samuel Thibault wrote:
> Juergen Gross, le dim. 19 juin 2022 08:52:52 +0200, a ecrit:
>> When getting the current allocation from Xen, this value includes the
>> pages allocated in the MMIO area. Fix the highest available RAM page
>> by subtracting the size of that area.
>>
>> This requires to read the E820 map before needing this value. Add two
>> functions returning the current and the maximum number of RAM pages
>> taking this correction into account.
>>
>> At the same time add the LAPIC page to the memory map in order to
>> avoid reusing that PFN for internal purposes.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> ---
>> V2:
>> - make e820_initial_reserved_pfns static (Samuel Thibault)
>> - add e820_get_current_pages() and e820_get_max_pages()
>> ---
> 
>> diff --git a/include/e820.h b/include/e820.h
>> index 5438a7c8..6f15fcd2 100644
>> --- a/include/e820.h
>> +++ b/include/e820.h
>> @@ -52,6 +52,8 @@ struct __packed e820entry {
>>   extern struct e820entry e820_map[];
>>   extern unsigned e820_entries;
>>   
>> +unsigned int e820_get_current_pages(void);
>> +unsigned int e820_get_max_pages(void);
> 
> Why an int rather than a long int? Yes 4TiB memory is large for mini-os,
> but better keep numbers of pages a long?

I don't think it matters that much (currently Mini-OS can't support more
than 512GiB of memory), but I can change the functions to unsigned long.

> 
> Apart from that,
> 
> Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

Thanks,


Juergen
diff mbox series

Patch

diff --git a/arch/x86/mm.c b/arch/x86/mm.c
index 41fcee67..cfc978f6 100644
--- a/arch/x86/mm.c
+++ b/arch/x86/mm.c
@@ -107,25 +107,20 @@  desc_ptr idt_ptr =
 
 void arch_mm_preinit(void *p)
 {
-    long ret;
-    domid_t domid = DOMID_SELF;
+    unsigned int pages;
     struct hvm_start_info *hsi = p;
 
     if ( hsi->version >= 1 && hsi->memmap_entries > 0 )
         e820_init_memmap((struct hvm_memmap_table_entry *)(unsigned long)
                          hsi->memmap_paddr, hsi->memmap_entries);
+    else
+        e820_init_memmap(NULL, 0);
 
     pt_base = page_table_base;
     first_free_pfn = PFN_UP(to_phys(&_end));
-    ret = HYPERVISOR_memory_op(XENMEM_current_reservation, &domid);
-    if ( ret < 0 )
-    {
-        xprintk("could not get memory size\n");
-        do_exit();
-    }
-
-    last_free_pfn = e820_get_maxpfn(ret);
-    balloon_set_nr_pages(ret, last_free_pfn);
+    pages = e820_get_current_pages();
+    last_free_pfn = e820_get_maxpfn(pages);
+    balloon_set_nr_pages(pages, last_free_pfn);
 }
 #endif
 
diff --git a/balloon.c b/balloon.c
index 9dc77c54..6ad07644 100644
--- a/balloon.c
+++ b/balloon.c
@@ -44,20 +44,12 @@  void balloon_set_nr_pages(unsigned long pages, unsigned long pfn)
 
 void get_max_pages(void)
 {
-    long ret;
-    domid_t domid = DOMID_SELF;
-
-    ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
-    if ( ret < 0 )
+    nr_max_pages = e820_get_max_pages();
+    if ( nr_max_pages )
     {
-        printk("Could not get maximum pfn\n");
-        return;
+        printk("Maximum memory size: %ld pages\n", nr_max_pages);
+        nr_max_pfn = e820_get_maxpfn(nr_max_pages);
     }
-
-    nr_max_pages = ret;
-    printk("Maximum memory size: %ld pages\n", nr_max_pages);
-
-    nr_max_pfn = e820_get_maxpfn(nr_max_pages);
 }
 
 void mm_alloc_bitmap_remap(void)
diff --git a/e820.c b/e820.c
index ad91e00b..48c9eadc 100644
--- a/e820.c
+++ b/e820.c
@@ -29,6 +29,38 @@ 
 #include <mini-os/e820.h>
 #include <xen/memory.h>
 
+static unsigned int e820_initial_reserved_pfns;
+
+unsigned int e820_get_current_pages(void)
+{
+    domid_t domid = DOMID_SELF;
+    long ret;
+
+    ret = HYPERVISOR_memory_op(XENMEM_current_reservation, &domid);
+    if ( ret < 0 )
+    {
+        xprintk("could not get memory size\n");
+        do_exit();
+    }
+
+    return ret - e820_initial_reserved_pfns;
+}
+
+unsigned int e820_get_max_pages(void)
+{
+    domid_t domid = DOMID_SELF;
+    long ret;
+
+    ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
+    if ( ret < 0 )
+    {
+        printk("Could not get maximum pfn\n");
+        return 0;
+    }
+
+    return ret - e820_initial_reserved_pfns;
+}
+
 #ifdef CONFIG_E820_TRIVIAL
 struct e820entry e820_map[1] = {
     {
@@ -40,10 +72,6 @@  struct e820entry e820_map[1] = {
 
 unsigned e820_entries = 1;
 
-static void e820_get_memmap(void)
-{
-}
-
 #else
 struct e820entry e820_map[E820_MAX];
 unsigned e820_entries;
@@ -199,6 +227,7 @@  static void e820_sanitize(void)
 {
     int i;
     unsigned long end, start;
+    bool found_lapic = false;
 
     /* Sanitize memory map in current form. */
     e820_process_entries();
@@ -238,8 +267,20 @@  static void e820_sanitize(void)
 
     /* Make remaining temporarily reserved entries permanently reserved. */
     for ( i = 0; i < e820_entries; i++ )
+    {
         if ( e820_map[i].type == E820_TMP_RESERVED )
             e820_map[i].type = E820_RESERVED;
+        if ( e820_map[i].type == E820_RESERVED )
+        {
+            e820_initial_reserved_pfns += e820_map[i].size / PAGE_SIZE;
+            if ( e820_map[i].addr <= LAPIC_ADDRESS &&
+                 e820_map[i].addr + e820_map[i].size > LAPIC_ADDRESS )
+                found_lapic = true;
+        }
+    }
+
+    if ( !found_lapic )
+        e820_insert_entry(LAPIC_ADDRESS, PAGE_SIZE, E820_RESERVED);
 }
 
 static void e820_get_memmap(void)
@@ -264,6 +305,12 @@  void e820_init_memmap(struct hvm_memmap_table_entry *entry, unsigned int num)
 {
     unsigned int i;
 
+    if ( !entry )
+    {
+        e820_get_memmap();
+        return;
+    }
+
     BUILD_BUG_ON(XEN_HVM_MEMMAP_TYPE_RAM != E820_RAM);
     BUILD_BUG_ON(XEN_HVM_MEMMAP_TYPE_RESERVED != E820_RESERVED);
     BUILD_BUG_ON(XEN_HVM_MEMMAP_TYPE_ACPI != E820_ACPI);
@@ -365,9 +412,6 @@  unsigned long e820_get_maxpfn(unsigned long pages)
     int i;
     unsigned long pfns = 0, start = 0;
 
-    if ( !e820_entries )
-        e820_get_memmap();
-
     for ( i = 0; i < e820_entries; i++ )
     {
         if ( e820_map[i].type != E820_RAM )
diff --git a/include/e820.h b/include/e820.h
index 5438a7c8..6f15fcd2 100644
--- a/include/e820.h
+++ b/include/e820.h
@@ -52,6 +52,8 @@  struct __packed e820entry {
 extern struct e820entry e820_map[];
 extern unsigned e820_entries;
 
+unsigned int e820_get_current_pages(void);
+unsigned int e820_get_max_pages(void);
 unsigned long e820_get_maxpfn(unsigned long pages);
 unsigned long e820_get_max_contig_pages(unsigned long pfn, unsigned long pages);
 #ifndef CONFIG_E820_TRIVIAL
diff --git a/include/x86/arch_mm.h b/include/x86/arch_mm.h
index ffbec5a8..a1b975dc 100644
--- a/include/x86/arch_mm.h
+++ b/include/x86/arch_mm.h
@@ -207,6 +207,8 @@  typedef unsigned long pgentry_t;
 /* to align the pointer to the (next) page boundary */
 #define PAGE_ALIGN(addr)        (((addr)+PAGE_SIZE-1)&PAGE_MASK)
 
+#define LAPIC_ADDRESS	CONST(0xfee00000)
+
 #ifndef __ASSEMBLY__
 /* Definitions for machine and pseudophysical addresses. */
 #ifdef __i386__