From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55554) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a8Ohd-0005VF-1H for qemu-devel@nongnu.org; Mon, 14 Dec 2015 03:41:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a8OhZ-0001ro-JH for qemu-devel@nongnu.org; Mon, 14 Dec 2015 03:41:52 -0500 Received: from mail-wm0-x22a.google.com ([2a00:1450:400c:c09::22a]:36722) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a8OhZ-0001rf-A9 for qemu-devel@nongnu.org; Mon, 14 Dec 2015 03:41:49 -0500 Received: by mail-wm0-x22a.google.com with SMTP id n186so107407546wmn.1 for ; Mon, 14 Dec 2015 00:41:49 -0800 (PST) From: Alvise Rigo Date: Mon, 14 Dec 2015 09:41:25 +0100 Message-Id: <1450082498-27109-2-git-send-email-a.rigo@virtualopensystems.com> In-Reply-To: <1450082498-27109-1-git-send-email-a.rigo@virtualopensystems.com> References: <1450082498-27109-1-git-send-email-a.rigo@virtualopensystems.com> Subject: [Qemu-devel] [RFC v6 01/14] exec.c: Add new exclusive bitmap to ram_list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, mttcg@listserver.greensocs.com Cc: claudio.fontana@huawei.com, pbonzini@redhat.com, jani.kokkonen@huawei.com, tech@virtualopensystems.com, alex.bennee@linaro.org, rth@twiddle.net The purpose of this new bitmap is to flag the memory pages that are in the middle of LL/SC operations (after a LL, before a SC) on a per-vCPU basis. For all these pages, the corresponding TLB entries will be generated in such a way to force the slow-path if at least one vCPU has the bit not set. When the system starts, the whole memory is dirty (all the bitmap is set). A page, after being marked as exclusively-clean, will be restored as dirty after the SC. For each page we keep 8 bits to be shared among all the vCPUs available in the system. In general, the to the vCPU n correspond the bit n % 8. Suggested-by: Jani Kokkonen Suggested-by: Claudio Fontana Signed-off-by: Alvise Rigo --- exec.c | 8 ++++-- include/exec/memory.h | 3 +- include/exec/ram_addr.h | 76 +++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 84 insertions(+), 3 deletions(-) diff --git a/exec.c b/exec.c index 0bf0a6e..e66d232 100644 --- a/exec.c +++ b/exec.c @@ -1548,11 +1548,15 @@ static ram_addr_t ram_block_add(RAMBlock *new_block, Error **errp) int i; /* ram_list.dirty_memory[] is protected by the iothread lock. */ - for (i = 0; i < DIRTY_MEMORY_NUM; i++) { + for (i = 0; i < DIRTY_MEMORY_EXCLUSIVE; i++) { ram_list.dirty_memory[i] = bitmap_zero_extend(ram_list.dirty_memory[i], old_ram_size, new_ram_size); - } + } + ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE] = bitmap_zero_extend( + ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE], + old_ram_size * EXCL_BITMAP_CELL_SZ, + new_ram_size * EXCL_BITMAP_CELL_SZ); } cpu_physical_memory_set_dirty_range(new_block->offset, new_block->used_length, diff --git a/include/exec/memory.h b/include/exec/memory.h index 0f07159..2782c77 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -19,7 +19,8 @@ #define DIRTY_MEMORY_VGA 0 #define DIRTY_MEMORY_CODE 1 #define DIRTY_MEMORY_MIGRATION 2 -#define DIRTY_MEMORY_NUM 3 /* num of dirty bits */ +#define DIRTY_MEMORY_EXCLUSIVE 3 +#define DIRTY_MEMORY_NUM 4 /* num of dirty bits */ #include #include diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index 7115154..b48af27 100644 --- a/include/exec/ram_addr.h +++ b/include/exec/ram_addr.h @@ -21,6 +21,7 @@ #ifndef CONFIG_USER_ONLY #include "hw/xen/xen.h" +#include "sysemu/sysemu.h" struct RAMBlock { struct rcu_head rcu; @@ -82,6 +83,13 @@ int qemu_ram_resize(ram_addr_t base, ram_addr_t newsize, Error **errp); #define DIRTY_CLIENTS_ALL ((1 << DIRTY_MEMORY_NUM) - 1) #define DIRTY_CLIENTS_NOCODE (DIRTY_CLIENTS_ALL & ~(1 << DIRTY_MEMORY_CODE)) +/* Exclusive bitmap support. */ +#define EXCL_BITMAP_CELL_SZ 8 +#define EXCL_BITMAP_GET_BIT_OFFSET(addr) \ + (EXCL_BITMAP_CELL_SZ * (addr >> TARGET_PAGE_BITS)) +#define EXCL_BITMAP_GET_BYTE_OFFSET(addr) (addr >> TARGET_PAGE_BITS) +#define EXCL_IDX(cpu) (cpu % EXCL_BITMAP_CELL_SZ) + static inline bool cpu_physical_memory_get_dirty(ram_addr_t start, ram_addr_t length, unsigned client) @@ -173,6 +181,11 @@ static inline void cpu_physical_memory_set_dirty_range(ram_addr_t start, if (unlikely(mask & (1 << DIRTY_MEMORY_CODE))) { bitmap_set_atomic(d[DIRTY_MEMORY_CODE], page, end - page); } + if (unlikely(mask & (1 << DIRTY_MEMORY_EXCLUSIVE))) { + bitmap_set_atomic(d[DIRTY_MEMORY_EXCLUSIVE], + page * EXCL_BITMAP_CELL_SZ, + (end - page) * EXCL_BITMAP_CELL_SZ); + } xen_modified_memory(start, length); } @@ -288,5 +301,68 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest, } void migration_bitmap_extend(ram_addr_t old, ram_addr_t new); + +/* One cell for each page. The n-th bit of a cell describes all the i-th vCPUs + * such that (i % EXCL_BITMAP_CELL_SZ) == n. + * A bit set to zero ensures that all the vCPUs described by the bit have the + * EXCL_BIT set for the page. */ +static inline void cpu_physical_memory_unset_excl(ram_addr_t addr, uint32_t cpu) +{ + set_bit_atomic(EXCL_BITMAP_GET_BIT_OFFSET(addr) + EXCL_IDX(cpu), + ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE]); +} + +/* Return true if there is at least one cpu with the EXCL bit set for the page + * of @addr. */ +static inline int cpu_physical_memory_atleast_one_excl(ram_addr_t addr) +{ + uint8_t *bitmap; + + bitmap = (uint8_t *)(ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE]); + + /* This is safe even if smp_cpus < 8 since the unused bits are always 1. */ + return bitmap[EXCL_BITMAP_GET_BYTE_OFFSET(addr)] != UCHAR_MAX; +} + +/* Return true if the @cpu has the bit set (not exclusive) for the page of + * @addr. If @cpu == smp_cpus return true if at least one vCPU has the dirty + * bit set for that page. */ +static inline int cpu_physical_memory_not_excl(ram_addr_t addr, + unsigned long cpu) +{ + uint8_t *bitmap; + + bitmap = (uint8_t *)ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE]; + + if (cpu == smp_cpus) { + if (smp_cpus >= EXCL_BITMAP_CELL_SZ) { + return bitmap[EXCL_BITMAP_GET_BYTE_OFFSET(addr)]; + } else { + return bitmap[EXCL_BITMAP_GET_BYTE_OFFSET(addr)] & + ((1 << smp_cpus) - 1); + } + } else { + return bitmap[EXCL_BITMAP_GET_BYTE_OFFSET(addr)] & (1 << EXCL_IDX(cpu)); + } +} + +/* Clean the dirty bit of @cpu (i.e. set the page as exclusive). If @cpu == + * smp_cpus clean the dirty bit for all the vCPUs. */ +static inline int cpu_physical_memory_set_excl(ram_addr_t addr, uint32_t cpu) +{ + if (cpu == smp_cpus) { + int nr = (smp_cpus >= EXCL_BITMAP_CELL_SZ) ? + EXCL_BITMAP_CELL_SZ : smp_cpus; + + return bitmap_test_and_clear_atomic( + ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE], + EXCL_BITMAP_GET_BIT_OFFSET(addr), nr); + } else { + return bitmap_test_and_clear_atomic( + ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE], + EXCL_BITMAP_GET_BIT_OFFSET(addr) + EXCL_IDX(cpu), 1); + } +} + #endif #endif -- 2.6.4