From patchwork Tue Sep 14 15:52:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Levitsky X-Patchwork-Id: 12494071 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3062C4332F for ; Tue, 14 Sep 2021 15:52:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B80AE61247 for ; Tue, 14 Sep 2021 15:52:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234762AbhINPxq (ORCPT ); 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Tue, 14 Sep 2021 15:52:22 +0000 (UTC) Received: from localhost.localdomain (unknown [10.35.206.50]) by smtp.corp.redhat.com (Postfix) with ESMTP id DE4F05D9D3; Tue, 14 Sep 2021 15:52:20 +0000 (UTC) From: Maxim Levitsky To: qemu-devel@nongnu.org Cc: Marcelo Tosatti , Paolo Bonzini , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , kvm@vger.kernel.org, =?utf-8?q?Alex_Benn=C3=A9e?= , Maxim Levitsky Subject: [PATCH 2/3] gdbstub: implement NOIRQ support for single step on KVM Date: Tue, 14 Sep 2021 18:52:13 +0300 Message-Id: <20210914155214.105415-3-mlevitsk@redhat.com> In-Reply-To: <20210914155214.105415-1-mlevitsk@redhat.com> References: <20210914155214.105415-1-mlevitsk@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Signed-off-by: Maxim Levitsky --- accel/kvm/kvm-all.c | 25 ++++++++++++++++++ gdbstub.c | 60 ++++++++++++++++++++++++++++++++++++-------- include/sysemu/kvm.h | 13 ++++++++++ 3 files changed, 88 insertions(+), 10 deletions(-) diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index 6b187e9c96..e141260796 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -169,6 +169,8 @@ bool kvm_vm_attributes_allowed; bool kvm_direct_msi_allowed; bool kvm_ioeventfd_any_length_allowed; bool kvm_msi_use_devid; +bool kvm_has_guest_debug; +int kvm_sstep_flags; static bool kvm_immediate_exit; static hwaddr kvm_max_slot_size = ~0; @@ -2559,6 +2561,25 @@ static int kvm_init(MachineState *ms) kvm_sregs2 = (kvm_check_extension(s, KVM_CAP_SREGS2) > 0); + kvm_has_guest_debug = + (kvm_check_extension(s, KVM_CAP_SET_GUEST_DEBUG) > 0); + + kvm_sstep_flags = 0; + + if (kvm_has_guest_debug) { + /* Assume that single stepping is supported */ + kvm_sstep_flags = SSTEP_ENABLE; + + int guest_debug_flags = + kvm_check_extension(s, KVM_CAP_SET_GUEST_DEBUG2); + + if (guest_debug_flags > 0) { + if (guest_debug_flags & KVM_GUESTDBG_BLOCKIRQ) { + kvm_sstep_flags |= SSTEP_NOIRQ; + } + } + } + kvm_state = s; ret = kvm_arch_init(ms, s); @@ -3188,6 +3209,10 @@ int kvm_update_guest_debug(CPUState *cpu, unsigned long reinject_trap) if (cpu->singlestep_enabled) { data.dbg.control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP; + + if (cpu->singlestep_enabled & SSTEP_NOIRQ) { + data.dbg.control |= KVM_GUESTDBG_BLOCKIRQ; + } } kvm_arch_update_guest_debug(cpu, &data.dbg); diff --git a/gdbstub.c b/gdbstub.c index 5d8e6ae3cd..48bb803bae 100644 --- a/gdbstub.c +++ b/gdbstub.c @@ -368,12 +368,11 @@ typedef struct GDBState { gdb_syscall_complete_cb current_syscall_cb; GString *str_buf; GByteArray *mem_buf; + int sstep_flags; + int supported_sstep_flags; } GDBState; -/* By default use no IRQs and no timers while single stepping so as to - * make single stepping like an ICE HW step. - */ -static int sstep_flags = SSTEP_ENABLE|SSTEP_NOIRQ|SSTEP_NOTIMER; +static GDBState gdbserver_state; /* Retrieves flags for single step mode. */ static int get_sstep_flags(void) @@ -385,11 +384,10 @@ static int get_sstep_flags(void) if (replay_mode != REPLAY_MODE_NONE) { return SSTEP_ENABLE; } else { - return sstep_flags; + return gdbserver_state.sstep_flags; } } -static GDBState gdbserver_state; static void init_gdbserver_state(void) { @@ -399,6 +397,23 @@ static void init_gdbserver_state(void) gdbserver_state.str_buf = g_string_new(NULL); gdbserver_state.mem_buf = g_byte_array_sized_new(MAX_PACKET_LENGTH); gdbserver_state.last_packet = g_byte_array_sized_new(MAX_PACKET_LENGTH + 4); + + + if (kvm_enabled()) { + gdbserver_state.supported_sstep_flags = kvm_get_supported_sstep_flags(); + } else { + gdbserver_state.supported_sstep_flags = + SSTEP_ENABLE | SSTEP_NOIRQ | SSTEP_NOTIMER; + } + + /* + * By default use no IRQs and no timers while single stepping so as to + * make single stepping like an ICE HW step. + */ + + gdbserver_state.sstep_flags = SSTEP_ENABLE | SSTEP_NOIRQ | SSTEP_NOTIMER; + gdbserver_state.sstep_flags &= gdbserver_state.supported_sstep_flags; + } #ifndef CONFIG_USER_ONLY @@ -2017,24 +2032,44 @@ static void handle_v_commands(GArray *params, void *user_ctx) static void handle_query_qemu_sstepbits(GArray *params, void *user_ctx) { - g_string_printf(gdbserver_state.str_buf, "ENABLE=%x,NOIRQ=%x,NOTIMER=%x", - SSTEP_ENABLE, SSTEP_NOIRQ, SSTEP_NOTIMER); + g_string_printf(gdbserver_state.str_buf, "ENABLE=%x", SSTEP_ENABLE); + + if (gdbserver_state.supported_sstep_flags & SSTEP_NOIRQ) { + g_string_append_printf(gdbserver_state.str_buf, ",NOIRQ=%x", + SSTEP_NOIRQ); + } + + if (gdbserver_state.supported_sstep_flags & SSTEP_NOTIMER) { + g_string_append_printf(gdbserver_state.str_buf, ",NOTIMER=%x", + SSTEP_NOTIMER); + } + put_strbuf(); } static void handle_set_qemu_sstep(GArray *params, void *user_ctx) { + int new_sstep_flags; + if (!params->len) { return; } - sstep_flags = get_param(params, 0)->val_ul; + new_sstep_flags = get_param(params, 0)->val_ul; + + if (new_sstep_flags & ~gdbserver_state.supported_sstep_flags) { + put_packet("E22"); + return; + } + + gdbserver_state.sstep_flags = new_sstep_flags; put_packet("OK"); } static void handle_query_qemu_sstep(GArray *params, void *user_ctx) { - g_string_printf(gdbserver_state.str_buf, "0x%x", sstep_flags); + g_string_printf(gdbserver_state.str_buf, "0x%x", + gdbserver_state.sstep_flags); put_strbuf(); } @@ -3493,6 +3528,11 @@ int gdbserver_start(const char *device) return -1; } + if (kvm_enabled() && !kvm_supports_guest_debug()) { + error_report("gdbstub: KVM doesn't support guest debugging"); + return -1; + } + if (!device) return -1; if (strcmp(device, "none") != 0) { diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h index b3d4538c55..9c0665363d 100644 --- a/include/sysemu/kvm.h +++ b/include/sysemu/kvm.h @@ -47,6 +47,8 @@ extern bool kvm_readonly_mem_allowed; extern bool kvm_direct_msi_allowed; extern bool kvm_ioeventfd_any_length_allowed; extern bool kvm_msi_use_devid; +extern bool kvm_has_guest_debug; +extern int kvm_sstep_flags; #define kvm_enabled() (kvm_allowed) /** @@ -171,6 +173,17 @@ extern bool kvm_msi_use_devid; */ #define kvm_msi_devid_required() (kvm_msi_use_devid) +/* + * Does KVM support guest debugging + */ +#define kvm_supports_guest_debug() (kvm_has_guest_debug) + +/* + * kvm_supported_sstep_flags + * Returns: SSTEP_* flags that KVM supports for guest debug + */ +#define kvm_get_supported_sstep_flags() (kvm_sstep_flags) + #else #define kvm_enabled() (0)