From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-178.mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3C96D1F5F6 for ; Mon, 9 Dec 2024 18:10:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733767827; cv=none; b=mJgNp9o8lP/Nap6dwT0jmWK+wnFMhthR74ZVYQAlat30ejkpLN61ZQak5Gi0EGvEqf0/lLaJvHO9gMgZAQ2ClrqeRdfFT1UyHSNJcti/IhLJRVgR6OPh/jhURm7dllyghq2pdX7G+qVl6LGxqG7f0a3sWzVF1NJgHZI4dfjuVeQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733767827; c=relaxed/simple; bh=kFmrffjPTHDvLRIbu40Zh3UrO4tcLxijJtAEeehy6K4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=FAnKTMje5/aF00YoCEYDSTFnfT/WDCnhvBKi6LvHjKnWuDJPL2oON82tEUWNoZDo1BYDtFtF4yi09dhzCegdNEKGjzQzU/iDt3onnaRr9GyRDHVJt3eZ6UKjAaL9dX9nSz9hqTzTqaw1NQ+vdkHPqwiJ+lHirsyjwjvb43I920o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=SFY9UQzX; arc=none smtp.client-ip=91.218.175.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="SFY9UQzX" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1733767821; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=f9yi0YOOYNDdJkqxrDH6/EGfgIdV/7SSosb9MoUMaTM=; b=SFY9UQzXjyLjf7j3qUTCS3nTxKcRG+qUiqcF+MBkwewOt3CDnplkkm7tuSa4N432D/WeFb kHz+7YuvQCls3UUldPN6/WoGNvBXqQHQ8vAOplPQbljVQkoo+73f4+IL2hZfof5JeThkiR Y9vf4HxcLL57dJFUyJoScpl07N21n8Q= From: Oliver Upton To: kvmarm@lists.linux.dev Cc: Marc Zyngier , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Mingwei Zhang , Colton Lewis , Raghavendra Rao Ananta , James Clark , Oliver Upton Subject: [PATCH v3 16/16] KVM: arm64: Avoid reading ID_AA64DFR0_EL1 for debug save/restore Date: Mon, 9 Dec 2024 10:09:26 -0800 Message-Id: <20241209180926.2161373-17-oliver.upton@linux.dev> In-Reply-To: <20241209180926.2161373-1-oliver.upton@linux.dev> References: <20241209180926.2161373-1-oliver.upton@linux.dev> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Similar to other per-CPU profiling/debug features we handle, store the number of breakpoints/watchpoints in kvm_host_data to avoid reading the ID register 4 times on every guest entry/exit. And if you're in the nested virt business that's quite a few avoidable exits to the L0 hypervisor. Signed-off-by: Oliver Upton --- arch/arm64/include/asm/kvm_host.h | 4 ++++ arch/arm64/kvm/debug.c | 3 +++ arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 17 ++++------------- 3 files changed, 11 insertions(+), 13 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index d48516de778d..e7c740c99ee3 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -661,6 +661,10 @@ struct kvm_host_data { /* Number of programmable event counters (PMCR_EL0.N) for this CPU */ unsigned int nr_event_counters; + + /* Number of debug breakpoints/watchpoints for this CPU (minus 1) */ + unsigned int debug_brps; + unsigned int debug_wrps; }; struct kvm_host_psci_config { diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 2b2065c94251..3bff1b8dccc4 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -63,6 +63,9 @@ void kvm_init_host_debug_data(void) *host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N, read_sysreg(pmcr_el0)); + *host_data_ptr(debug_brps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, dfr0); + *host_data_ptr(debug_wrps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, dfr0); + if (has_vhe()) return; diff --git a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h index c14586d87361..502a5b73ee70 100644 --- a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h +++ b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h @@ -106,12 +106,8 @@ static struct kvm_guest_debug_arch *__vcpu_debug_regs(struct kvm_vcpu *vcpu) static void __debug_save_state(struct kvm_guest_debug_arch *dbg, struct kvm_cpu_context *ctxt) { - u64 aa64dfr0; - int brps, wrps; - - aa64dfr0 = read_sysreg(id_aa64dfr0_el1); - brps = (aa64dfr0 >> 12) & 0xf; - wrps = (aa64dfr0 >> 20) & 0xf; + int brps = *host_data_ptr(debug_brps); + int wrps = *host_data_ptr(debug_wrps); save_debug(dbg->dbg_bcr, dbgbcr, brps); save_debug(dbg->dbg_bvr, dbgbvr, brps); @@ -124,13 +120,8 @@ static void __debug_save_state(struct kvm_guest_debug_arch *dbg, static void __debug_restore_state(struct kvm_guest_debug_arch *dbg, struct kvm_cpu_context *ctxt) { - u64 aa64dfr0; - int brps, wrps; - - aa64dfr0 = read_sysreg(id_aa64dfr0_el1); - - brps = (aa64dfr0 >> 12) & 0xf; - wrps = (aa64dfr0 >> 20) & 0xf; + int brps = *host_data_ptr(debug_brps); + int wrps = *host_data_ptr(debug_wrps); restore_debug(dbg->dbg_bcr, dbgbcr, brps); restore_debug(dbg->dbg_bvr, dbgbvr, brps); -- 2.39.5