diff options
| -rw-r--r-- | arch/x86/xen/p2m.c | 155 |
1 files changed, 105 insertions, 50 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 82c8c9305510..57001443231e 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -36,7 +36,7 @@ * pfn_to_mfn(0xc0000)=0xc0000 * * The benefit of this is, that we can assume for non-RAM regions (think - * PCI BARs, or ACPI spaces), we can create mappings easily b/c we + * PCI BARs, or ACPI spaces), we can create mappings easily because we * get the PFN value to match the MFN. * * For this to work efficiently we have one new page p2m_identity and @@ -60,7 +60,7 @@ * There is also a digram of the P2M at the end that can help. * Imagine your E820 looking as so: * - * 1GB 2GB + * 1GB 2GB 4GB * /-------------------+---------\/----\ /----------\ /---+-----\ * | System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM | * \-------------------+---------/\----/ \----------/ \---+-----/ @@ -77,9 +77,8 @@ * of the PFN and the end PFN (263424 and 512256 respectively). The first step * is to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page * covers 512^2 of page estate (1GB) and in case the start or end PFN is not - * aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn - * to end pfn. We reserve_brk top leaf pages if they are missing (means they - * point to p2m_mid_missing). + * aligned on 512^2*PAGE_SIZE (1GB) we reserve_brk new middle and leaf pages as + * required to split any existing p2m_mid_missing middle pages. * * With the E820 example above, 263424 is not 1GB aligned so we allocate a * reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000. @@ -88,7 +87,7 @@ * Next stage is to determine if we need to do a more granular boundary check * on the 4MB (or 2MB depending on architecture) off the start and end pfn's. * We check if the start pfn and end pfn violate that boundary check, and if - * so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer + * so reserve_brk a (p2m[x][y]) leaf page. This way we have a much finer * granularity of setting which PFNs are missing and which ones are identity. * In our example 263424 and 512256 both fail the check so we reserve_brk two * pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" @@ -102,9 +101,10 @@ * * The next step is to walk from the start pfn to the end pfn setting * the IDENTITY_FRAME_BIT on each PFN. This is done in set_phys_range_identity. - * If we find that the middle leaf is pointing to p2m_missing we can swap it - * over to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this - * point we do not need to worry about boundary aligment (so no need to + * If we find that the middle entry is pointing to p2m_missing we can swap it + * over to p2m_identity - this way covering 4MB (or 2MB) PFN space (and + * similarly swapping p2m_mid_missing for p2m_mid_identity for larger regions). + * At this point we do not need to worry about boundary aligment (so no need to * reserve_brk a middle page, figure out which PFNs are "missing" and which * ones are identity), as that has been done earlier. If we find that the * middle leaf is not occupied by p2m_identity or p2m_missing, we dereference @@ -118,6 +118,9 @@ * considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511] * contain the INVALID_P2M_ENTRY value and are considered "missing." * + * Finally, the region beyond the end of of the E820 (4 GB in this example) + * is set to be identity (in case there are MMIO regions placed here). + * * This is what the p2m ends up looking (for the E820 above) with this * fabulous drawing: * @@ -129,21 +132,27 @@ * |-----| \ | [p2m_identity]+\\ | .... | * | 2 |--\ \-------------------->| ... | \\ \----------------/ * |-----| \ \---------------/ \\ - * | 3 |\ \ \\ p2m_identity - * |-----| \ \-------------------->/---------------\ /-----------------\ - * | .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... | - * \-----/ / | [p2m_identity]+-->| ..., ~0 | - * / /---------------\ | .... | \-----------------/ - * / | IDENTITY[@0] | /-+-[x], ~0, ~0.. | - * / | IDENTITY[@256]|<----/ \---------------/ - * / | ~0, ~0, .... | - * | \---------------/ - * | - * p2m_mid_missing p2m_missing - * /-----------------\ /------------\ - * | [p2m_missing] +---->| ~0, ~0, ~0 | - * | [p2m_missing] +---->| ..., ~0 | - * \-----------------/ \------------/ + * | 3 |-\ \ \\ p2m_identity [1] + * |-----| \ \-------------------->/---------------\ /-----------------\ + * | .. |\ | | [p2m_identity]+-->| ~0, ~0, ~0, ... | + * \-----/ | | | [p2m_identity]+-->| ..., ~0 | + * | | | .... | \-----------------/ + * | | +-[x], ~0, ~0.. +\ + * | | \---------------/ \ + * | | \-> /---------------\ + * | V p2m_mid_missing p2m_missing | IDENTITY[@0] | + * | /-----------------\ /------------\ | IDENTITY[@256]| + * | | [p2m_missing] +---->| ~0, ~0, ...| | ~0, ~0, .... | + * | | [p2m_missing] +---->| ..., ~0 | \---------------/ + * | | ... | \------------/ + * | \-----------------/ + * | + * | p2m_mid_identity + * | /-----------------\ + * \-->| [p2m_identity] +---->[1] + * | [p2m_identity] +---->[1] + * | ... | + * \-----------------/ * * where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT) */ @@ -187,13 +196,15 @@ static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE); static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE); static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE); +static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_identity, P2M_MID_PER_PAGE); +static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_identity_mfn, P2M_MID_PER_PAGE); RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE))); RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE))); /* We might hit two boundary violations at the start and end, at max each * boundary violation will require three middle nodes. */ -RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3); +RESERVE_BRK(p2m_mid_extra, PAGE_SIZE * 2 * 3); /* When we populate back during bootup, the amount of pages can vary. The * max we have is seen is 395979, but that does not mean it can't be more. @@ -242,20 +253,20 @@ static void p2m_top_mfn_p_init(unsigned long **top) top[i] = p2m_mid_missing_mfn; } -static void p2m_mid_init(unsigned long **mid) +static void p2m_mid_init(unsigned long **mid, unsigned long *leaf) { unsigned i; for (i = 0; i < P2M_MID_PER_PAGE; i++) - mid[i] = p2m_missing; + mid[i] = leaf; } -static void p2m_mid_mfn_init(unsigned long *mid) +static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf) { unsigned i; for (i = 0; i < P2M_MID_PER_PAGE; i++) - mid[i] = virt_to_mfn(p2m_missing); + mid[i] = virt_to_mfn(leaf); } static void p2m_init(unsigned long *p2m) @@ -286,7 +297,9 @@ void __ref xen_build_mfn_list_list(void) /* Pre-initialize p2m_top_mfn to be completely missing */ if (p2m_top_mfn == NULL) { p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE); - p2m_mid_mfn_init(p2m_mid_missing_mfn); + p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); + p2m_mid_identity_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE); + p2m_mid_mfn_init(p2m_mid_identity_mfn, p2m_identity); p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); p2m_top_mfn_p_init(p2m_top_mfn_p); @@ -295,7 +308,8 @@ void __ref xen_build_mfn_list_list(void) p2m_top_mfn_init(p2m_top_mfn); } else { /* Reinitialise, mfn's all change after migration */ - p2m_mid_mfn_init(p2m_mid_missing_mfn); + p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); + p2m_mid_mfn_init(p2m_mid_identity_mfn, p2m_identity); } for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) { @@ -327,7 +341,7 @@ void __ref xen_build_mfn_list_list(void) * it too late. */ mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); - p2m_mid_mfn_init(mid_mfn_p); + p2m_mid_mfn_init(mid_mfn_p, p2m_missing); p2m_top_mfn_p[topidx] = mid_mfn_p; } @@ -365,16 +379,17 @@ void __init xen_build_dynamic_phys_to_machine(void) p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); p2m_init(p2m_missing); + p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE); + p2m_init(p2m_identity); p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); - p2m_mid_init(p2m_mid_missing); + p2m_mid_init(p2m_mid_missing, p2m_missing); + p2m_mid_identity = extend_brk(PAGE_SIZE, PAGE_SIZE); + p2m_mid_init(p2m_mid_identity, p2m_identity); p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE); p2m_top_init(p2m_top); - p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE); - p2m_init(p2m_identity); - /* * The domain builder gives us a pre-constructed p2m array in * mfn_list for all the pages initially given to us, so we just @@ -386,7 +401,7 @@ void __init xen_build_dynamic_phys_to_machine(void) if (p2m_top[topidx] == p2m_mid_missing) { unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE); - p2m_mid_init(mid); + p2m_mid_init(mid, p2m_missing); p2m_top[topidx] = mid; } @@ -545,7 +560,7 @@ static bool alloc_p2m(unsigned long pfn) if (!mid) return false; - p2m_mid_init(mid); + p2m_mid_init(mid, p2m_missing); if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing) free_p2m_page(mid); @@ -565,7 +580,7 @@ static bool alloc_p2m(unsigned long pfn) if (!mid_mfn) return false; - p2m_mid_mfn_init(mid_mfn); + p2m_mid_mfn_init(mid_mfn, p2m_missing); missing_mfn = virt_to_mfn(p2m_mid_missing_mfn); mid_mfn_mfn = virt_to_mfn(mid_mfn); @@ -649,7 +664,7 @@ static bool __init early_alloc_p2m_middle(unsigned long pfn) if (mid == p2m_mid_missing) { mid = extend_brk(PAGE_SIZE, PAGE_SIZE); - p2m_mid_init(mid); + p2m_mid_init(mid, p2m_missing); p2m_top[topidx] = mid; @@ -658,7 +673,7 @@ static bool __init early_alloc_p2m_middle(unsigned long pfn) /* And the save/restore P2M tables.. */ if (mid_mfn_p == p2m_mid_missing_mfn) { mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); - p2m_mid_mfn_init(mid_mfn_p); + p2m_mid_mfn_init(mid_mfn_p, p2m_missing); p2m_top_mfn_p[topidx] = mid_mfn_p; p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p); @@ -769,6 +784,24 @@ bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn) return true; } + +static void __init early_split_p2m(unsigned long pfn) +{ + unsigned long mididx, idx; + + mididx = p2m_mid_index(pfn); + idx = p2m_index(pfn); + + /* + * Allocate new middle and leaf pages if this pfn lies in the + * middle of one. + */ + if (mididx || idx) + early_alloc_p2m_middle(pfn); + if (idx) + early_alloc_p2m(pfn, false); +} + unsigned long __init set_phys_range_identity(unsigned long pfn_s, unsigned long pfn_e) { @@ -786,19 +819,27 @@ unsigned long __init set_phys_range_identity(unsigned long pfn_s, if (pfn_e > MAX_P2M_PFN) pfn_e = MAX_P2M_PFN; - for (pfn = (pfn_s & ~(P2M_MID_PER_PAGE * P2M_PER_PAGE - 1)); - pfn < ALIGN(pfn_e, (P2M_MID_PER_PAGE * P2M_PER_PAGE)); - pfn += P2M_MID_PER_PAGE * P2M_PER_PAGE) - { - WARN_ON(!early_alloc_p2m(pfn)); - } + early_split_p2m(pfn_s); + early_split_p2m(pfn_e); - early_alloc_p2m_middle(pfn_s, true); - early_alloc_p2m_middle(pfn_e, true); + for (pfn = pfn_s; pfn < pfn_e;) { + unsigned topidx = p2m_top_index(pfn); + unsigned mididx = p2m_mid_index(pfn); - for (pfn = pfn_s; pfn < pfn_e; pfn++) if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn))) break; + pfn++; + + /* + * If the PFN was set to a middle or leaf identity + * page the remainder must also be identity, so skip + * ahead to the next middle or leaf entry. + */ + if (p2m_top[topidx] == p2m_mid_identity) + pfn = ALIGN(pfn, P2M_MID_PER_PAGE * P2M_PER_PAGE); + else if (p2m_top[topidx][mididx] == p2m_identity) + pfn = ALIGN(pfn, P2M_PER_PAGE); + } if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s), "Identity mapping failed. We are %ld short of 1-1 mappings!\n", @@ -828,8 +869,22 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) /* For sparse holes were the p2m leaf has real PFN along with * PCI holes, stick in the PFN as the MFN value. + * + * set_phys_range_identity() will have allocated new middle + * and leaf pages as required so an existing p2m_mid_missing + * or p2m_missing mean that whole range will be identity so + * these can be switched to p2m_mid_identity or p2m_identity. */ if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) { + if (p2m_top[topidx] == p2m_mid_identity) + return true; + + if (p2m_top[topidx] == p2m_mid_missing) { + WARN_ON(cmpxchg(&p2m_top[topidx], p2m_mid_missing, + p2m_mid_identity) != p2m_mid_missing); + return true; + } + if (p2m_top[topidx][mididx] == p2m_identity) return true; |