From bb223055b9b327ec66e1f6d2fbaebaee0b8f3dbe Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Mon, 11 Dec 2017 13:21:46 +0100 Subject: [PATCH] s390-ccw-virtio: allow for systems larger that 7.999TB KVM does not allow memory regions > KVM_MEM_MAX_NR_PAGES, basically limiting the memory per slot to 8TB-4k. As memory slots on s390/kvm must be a multiple of 1MB we need start a new memory region if we cross 8TB-1M. With that (and optimistic overcommitment in the kernel) I was able to start a 24TB guest on a 1TB system. Signed-off-by: Christian Borntraeger Message-Id: <20171211122146.162430-1-borntraeger@de.ibm.com> Reviewed-by: David Hildenbrand [CH: 1UL -> 1ULL in KVM_MEM_MAX_NR_PAGES; build fix on 32 bit hosts] Signed-off-by: Cornelia Huck --- hw/s390x/s390-virtio-ccw.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c index 466e45343c..35df7e19c5 100644 --- a/hw/s390x/s390-virtio-ccw.c +++ b/hw/s390x/s390-virtio-ccw.c @@ -152,14 +152,38 @@ static void virtio_ccw_register_hcalls(void) virtio_ccw_hcall_early_printk); } +/* + * KVM does only support memory slots up to KVM_MEM_MAX_NR_PAGES pages + * as the dirty bitmap must be managed by bitops that take an int as + * position indicator. If we have a guest beyond that we will split off + * new subregions. The split must happen on a segment boundary (1MB). + */ +#define KVM_MEM_MAX_NR_PAGES ((1ULL << 31) - 1) +#define SEG_MSK (~0xfffffULL) +#define KVM_SLOT_MAX_BYTES ((KVM_MEM_MAX_NR_PAGES * TARGET_PAGE_SIZE) & SEG_MSK) static void s390_memory_init(ram_addr_t mem_size) { MemoryRegion *sysmem = get_system_memory(); - MemoryRegion *ram = g_new(MemoryRegion, 1); + ram_addr_t chunk, offset = 0; + unsigned int number = 0; + gchar *name; /* allocate RAM for core */ - memory_region_allocate_system_memory(ram, NULL, "s390.ram", mem_size); - memory_region_add_subregion(sysmem, 0, ram); + name = g_strdup_printf("s390.ram"); + while (mem_size) { + MemoryRegion *ram = g_new(MemoryRegion, 1); + uint64_t size = mem_size; + + /* KVM does not allow memslots >= 8 TB */ + chunk = MIN(size, KVM_SLOT_MAX_BYTES); + memory_region_allocate_system_memory(ram, NULL, name, chunk); + memory_region_add_subregion(sysmem, offset, ram); + mem_size -= chunk; + offset += chunk; + g_free(name); + name = g_strdup_printf("s390.ram.%u", ++number); + } + g_free(name); /* Initialize storage key device */ s390_skeys_init(); -- 2.11.4.GIT