From patchwork Thu Jul 29 12:48:01 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 60239 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from bilbo.ozlabs.org (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id 0B4BB102153 for ; Thu, 29 Jul 2010 22:50:03 +1000 (EST) Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by ozlabs.org (Postfix) with ESMTP id D04FEB7102 for ; Thu, 29 Jul 2010 22:48:13 +1000 (EST) Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.221.2]) by mx2.suse.de (Postfix) with ESMTP id 1863B89471; Thu, 29 Jul 2010 14:48:09 +0200 (CEST) From: Alexander Graf To: kvm-ppc@vger.kernel.org Subject: [PATCH 20/27] KVM: PPC: Introduce kvm_tmp framework Date: Thu, 29 Jul 2010 14:48:01 +0200 Message-Id: <1280407688-9815-21-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.6.0.2 In-Reply-To: <1280407688-9815-1-git-send-email-agraf@suse.de> References: <1280407688-9815-1-git-send-email-agraf@suse.de> Cc: linuxppc-dev , KVM list X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org We will soon require more sophisticated methods to replace single instructions with multiple instructions. We do that by branching to a memory region where we write replacement code for the instruction to. This region needs to be within 32 MB of the patched instruction though, because that's the furthest we can jump with immediate branches. So we keep 1MB of free space around in bss. After we're done initing we can just tell the mm system that the unused pages are free, but until then we have enough space to fit all our code in. Signed-off-by: Alexander Graf --- arch/powerpc/kernel/kvm.c | 42 ++++++++++++++++++++++++++++++++++++++++-- 1 files changed, 40 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c index 3258922..926f93f 100644 --- a/arch/powerpc/kernel/kvm.c +++ b/arch/powerpc/kernel/kvm.c @@ -65,6 +65,8 @@ #define KVM_INST_TLBSYNC 0x7c00046c static bool kvm_patching_worked = true; +static char kvm_tmp[1024 * 1024]; +static int kvm_tmp_index; static inline void kvm_patch_ins(u32 *inst, u32 new_inst) { @@ -105,6 +107,23 @@ static void kvm_patch_ins_nop(u32 *inst) kvm_patch_ins(inst, KVM_INST_NOP); } +static u32 *kvm_alloc(int len) +{ + u32 *p; + + if ((kvm_tmp_index + len) > ARRAY_SIZE(kvm_tmp)) { + printk(KERN_ERR "KVM: No more space (%d + %d)\n", + kvm_tmp_index, len); + kvm_patching_worked = false; + return NULL; + } + + p = (void*)&kvm_tmp[kvm_tmp_index]; + kvm_tmp_index += len; + + return p; +} + static void kvm_map_magic_page(void *data) { kvm_hypercall2(KVM_HC_PPC_MAP_MAGIC_PAGE, @@ -270,17 +289,36 @@ static int kvm_para_setup(void) return 0; } +static __init void kvm_free_tmp(void) +{ + unsigned long start, end; + + start = (ulong)&kvm_tmp[kvm_tmp_index + (PAGE_SIZE - 1)] & PAGE_MASK; + end = (ulong)&kvm_tmp[ARRAY_SIZE(kvm_tmp)] & PAGE_MASK; + + /* Free the tmp space we don't need */ + for (; start < end; start += PAGE_SIZE) { + ClearPageReserved(virt_to_page(start)); + init_page_count(virt_to_page(start)); + free_page(start); + totalram_pages++; + } +} + static int __init kvm_guest_init(void) { if (!kvm_para_available()) - return 0; + goto free_tmp; if (kvm_para_setup()) - return 0; + goto free_tmp; if (kvm_para_has_feature(KVM_FEATURE_MAGIC_PAGE)) kvm_use_magic_page(); +free_tmp: + kvm_free_tmp(); + return 0; }