From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 05D0B1D04BA; Wed, 2 Oct 2024 14:49:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727880542; cv=none; b=B559Q6i6/Q+qgynfAEy6wfxsSgIoCMd+4+n42gApof3s67d0MVU2zPWrSfApn2XV34Ei+GJ9ibaEkCzYd9m2+nj6o1ETrgV7NwjkMxPI4DdP2AD/3+c1MPCqlWwC19m5gNdt4Ju1eZQZPOCJ2ZToNdQz3fAsRCS3t7oN2j/92cY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727880542; c=relaxed/simple; bh=CQCiDmV3/aTYmfJRhG7WiFLluN/eGJabtfqYsislgrU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JNfqajvm4lrfpu4cTv8EtBZK3APm8Pd9OS1oS3oJeB+JuXhSt417A/R5SVD/xMqiyrxeKep9bjg3G/n6gGM7BccxQZSTdtuKL5jqeo2uDFaPCOKQYxNr+8RgDeXGGnpLhNMdn0Nx+TAFBsWV+EjTu1MeqFc5gEH59EYNiXdeutg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=g8yXzxch; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="g8yXzxch" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76205C4CEC2; Wed, 2 Oct 2024 14:49:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727880541; bh=CQCiDmV3/aTYmfJRhG7WiFLluN/eGJabtfqYsislgrU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=g8yXzxch69GfbEvAVTL8gDlyhMqBCku0qJC+/nw5Wt6D9c5UHojJuBH7yr5t2yx5t vUibx7H3N2+qpXMgATVXPGRoi4upOMSxNkPdhPtCzPWPA7FviltlFsxoeJtGOt3S/2 U/pgkuYeEzJDOy38LmzUZl5F35Qf3omqcT5QcLvg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Dmitry Vyukov , Thomas Gleixner , Alexander Potapenko , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 6.6 494/538] x86/entry: Remove unwanted instrumentation in common_interrupt() Date: Wed, 2 Oct 2024 15:02:13 +0200 Message-ID: <20241002125811.939707594@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241002125751.964700919@linuxfoundation.org> References: <20241002125751.964700919@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dmitry Vyukov [ Upstream commit 477d81a1c47a1b79b9c08fc92b5dea3c5143800b ] common_interrupt() and related variants call kvm_set_cpu_l1tf_flush_l1d(), which is neither marked noinstr nor __always_inline. So compiler puts it out of line and adds instrumentation to it. Since the call is inside of instrumentation_begin/end(), objtool does not warn about it. The manifestation is that KCOV produces spurious coverage in kvm_set_cpu_l1tf_flush_l1d() in random places because the call happens when preempt count is not yet updated to say that the kernel is in an interrupt. Mark kvm_set_cpu_l1tf_flush_l1d() as __always_inline and move it out of the instrumentation_begin/end() section. It only calls __this_cpu_write() which is already safe to call in noinstr contexts. Fixes: 6368558c3710 ("x86/entry: Provide IDTENTRY_SYSVEC") Signed-off-by: Dmitry Vyukov Signed-off-by: Thomas Gleixner Reviewed-by: Alexander Potapenko Acked-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/3f9a1de9e415fcb53d07dc9e19fa8481bb021b1b.1718092070.git.dvyukov@google.com Signed-off-by: Sasha Levin --- arch/x86/include/asm/hardirq.h | 8 ++++++-- arch/x86/include/asm/idtentry.h | 6 +++--- 2 files changed, 9 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h index 66837b8c67f1a..f2e245741afc2 100644 --- a/arch/x86/include/asm/hardirq.h +++ b/arch/x86/include/asm/hardirq.h @@ -63,7 +63,11 @@ extern u64 arch_irq_stat(void); #define local_softirq_pending_ref pcpu_hot.softirq_pending #if IS_ENABLED(CONFIG_KVM_INTEL) -static inline void kvm_set_cpu_l1tf_flush_l1d(void) +/* + * This function is called from noinstr interrupt contexts + * and must be inlined to not get instrumentation. + */ +static __always_inline void kvm_set_cpu_l1tf_flush_l1d(void) { __this_cpu_write(irq_stat.kvm_cpu_l1tf_flush_l1d, 1); } @@ -78,7 +82,7 @@ static __always_inline bool kvm_get_cpu_l1tf_flush_l1d(void) return __this_cpu_read(irq_stat.kvm_cpu_l1tf_flush_l1d); } #else /* !IS_ENABLED(CONFIG_KVM_INTEL) */ -static inline void kvm_set_cpu_l1tf_flush_l1d(void) { } +static __always_inline void kvm_set_cpu_l1tf_flush_l1d(void) { } #endif /* IS_ENABLED(CONFIG_KVM_INTEL) */ #endif /* _ASM_X86_HARDIRQ_H */ diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index e2585f61082cd..10603e185111d 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -212,8 +212,8 @@ __visible noinstr void func(struct pt_regs *regs, \ irqentry_state_t state = irqentry_enter(regs); \ u32 vector = (u32)(u8)error_code; \ \ + kvm_set_cpu_l1tf_flush_l1d(); \ instrumentation_begin(); \ - kvm_set_cpu_l1tf_flush_l1d(); \ run_irq_on_irqstack_cond(__##func, regs, vector); \ instrumentation_end(); \ irqentry_exit(regs, state); \ @@ -250,7 +250,6 @@ static void __##func(struct pt_regs *regs); \ \ static __always_inline void instr_##func(struct pt_regs *regs) \ { \ - kvm_set_cpu_l1tf_flush_l1d(); \ run_sysvec_on_irqstack_cond(__##func, regs); \ } \ \ @@ -258,6 +257,7 @@ __visible noinstr void func(struct pt_regs *regs) \ { \ irqentry_state_t state = irqentry_enter(regs); \ \ + kvm_set_cpu_l1tf_flush_l1d(); \ instrumentation_begin(); \ instr_##func (regs); \ instrumentation_end(); \ @@ -288,7 +288,6 @@ static __always_inline void __##func(struct pt_regs *regs); \ static __always_inline void instr_##func(struct pt_regs *regs) \ { \ __irq_enter_raw(); \ - kvm_set_cpu_l1tf_flush_l1d(); \ __##func (regs); \ __irq_exit_raw(); \ } \ @@ -297,6 +296,7 @@ __visible noinstr void func(struct pt_regs *regs) \ { \ irqentry_state_t state = irqentry_enter(regs); \ \ + kvm_set_cpu_l1tf_flush_l1d(); \ instrumentation_begin(); \ instr_##func (regs); \ instrumentation_end(); \ -- 2.43.0