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[195.149.20.212]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4562e7f2d4fsm954075e9.4.2025.07.15.13.46.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Jul 2025 13:46:30 -0700 (PDT) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: c9dd50a0-61bc-11f0-b894-0df219b8e170 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1752612391; x=1753217191; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=rpiN/L2/GYLFkGj+NQZ9/20Wx3+NoNPS3w4mMjkBd2g=; b=gRiAoc7xPV0e0S+MJVlqdm6Hi1je5+zq9ahrIKHwn/82Tsm++Ge1FwSuyFt9kZaErj kfo4CQAuaI/O7Z606ZR1tecswv5ys06FnbjK0P2f/W9/FfQLBr/LdscXfNv4ypCTNQYk 7SKgacx1fUr9h2NpWkbZADJRAu37Z3VhrgdjU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752612391; x=1753217191; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=rpiN/L2/GYLFkGj+NQZ9/20Wx3+NoNPS3w4mMjkBd2g=; b=g+oMRYGrWhk/YnRQ4ekVzOeaHHuFmHZEAX3Ty11XKOaxC9W/ecwou/+Iia17v6udWw V20W3SoxwMudpTnv4UBfhajmnJyDhSYpmZixOUPURUhYnLVEljUMxVw8vXWyo8bwshYW dqzXsWIRtaVKufz+m8YzJre2z9EjcBanRKdeXiJPEiwRHTtHMd3iVRYOr40BMovu1CrC HE4rge0lEwGzZPr33ANJWnEexPW3+g0SdNboHMIGMIcqspQNXhGKQ+OBPwPsbN1hqJGA PbcZKzIHpk1qiZA3v9ojN6915i1rS3ZY8UMA82MJ7K6CfDpCU4nDc0ig20ATBMFfXu8W bP0g== X-Gm-Message-State: AOJu0YxiIv6XNAPZOSIfwC4iej6+/ao+iGVU4VXCqXW8BTniuR2gwA3r 3te+z+6xS9NUcqVhLaOUk0ekRQRlHucNTVm73PlLTBwlhbAbK+bOYsLNqoysJdXyUmQF7EUudj/ WG1w07+WzhA== X-Gm-Gg: ASbGnctSIWqrSB9JysvB5nQ2kwV6GRZRnYyj0pim27U/dQuaG2ZhrijFNvslTrneD2N MubuxWrKgK0bNp9s+/g5UH2kG62DyzORat9iIkuvxQ9QaXhOwT2dliYZpXJaoDyIlytTGYFjkZ4 VFL7cUjybpjqCitO9XcKWbAlF1vz2UN334POtoFyFw7YEt73VjCdyWt9tIP7iRQQhJHofnEZRuk FZ1raUunIem7rhQye9ieDW0dpYTnje/QtfAIoUAsx7ZkUOkDO1oZ54vpDSKueTM1tC1jHJyiHo0 AmgXDSxYacJLhb4udoRsxLxYSPzL3H7Wt+LYZZd+fiRtFnWJ5zYMTjOmeuw8aWoTZPtAcq8X9h0 z2Lx5797y+IFf+1lWX4ju0kK6yO1FIbu6VYQ4WuqzpRSKMdJ5sM11ArA3exPLLM3GsKGqf7cMO3 7/ X-Google-Smtp-Source: AGHT+IGU9RIt9dX+nG5hvz0ICYWfap9LMZOHwo7MdiqjgwGzGoHpNySxgxADbY2N5cSSxyuRwgLcbw== X-Received: by 2002:a05:6000:288f:b0:3b6:489:b7e5 with SMTP id ffacd0b85a97d-3b60ddc5a47mr380487f8f.49.1752612390972; Tue, 15 Jul 2025 13:46:30 -0700 (PDT) From: Andrew Cooper To: Xen-devel Cc: Andrew Cooper , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Subject: [PATCH] x86: Drop rep_nop() and use the PAUSE mnemonic directly Date: Tue, 15 Jul 2025 21:46:28 +0100 Message-Id: <20250715204628.1848686-1-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.39.5 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @citrix.com) X-ZM-MESSAGEID: 1752612424352116600 In udelay(), use cpu_relax() directly which, for better or worse, is the common way to refer to the PAUSE instruction. No functional change. Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 --- xen/arch/x86/delay.c | 2 +- xen/arch/x86/include/asm/processor.h | 9 ++------- 2 files changed, 3 insertions(+), 8 deletions(-) diff --git a/xen/arch/x86/delay.c b/xen/arch/x86/delay.c index b3a41881a17a..ed093fbb0861 100644 --- a/xen/arch/x86/delay.c +++ b/xen/arch/x86/delay.c @@ -23,7 +23,7 @@ void udelay(unsigned long usecs) s =3D rdtsc_ordered(); do { - rep_nop(); + cpu_relax(); e =3D rdtsc_ordered(); } while ((e-s) < ticks); } diff --git a/xen/arch/x86/include/asm/processor.h b/xen/arch/x86/include/as= m/processor.h index 04824c3633cf..b6e8de5e864d 100644 --- a/xen/arch/x86/include/asm/processor.h +++ b/xen/arch/x86/include/asm/processor.h @@ -340,13 +340,8 @@ DECLARE_PER_CPU(root_pgentry_t *, root_pgt); =20 extern void write_ptbase(struct vcpu *v); =20 -/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */ -static always_inline void rep_nop(void) -{ - asm volatile ( "rep;nop" : : : "memory" ); -} - -#define cpu_relax() rep_nop() +/* PAUSE (encoding: REP NOP) is a good thing to insert into busy-wait loop= s. */ +#define cpu_relax() asm volatile ( "pause" ::: "memory" ) =20 void show_code(const struct cpu_user_regs *regs); void show_stack_overflow(unsigned int cpu, const struct cpu_user_regs *reg= s); --=20 2.39.5