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[195.149.20.212]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3bb5d089e07sm3153924f8f.0.2025.08.15.13.41.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Aug 2025 13:41:31 -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: 3a91e778-7a18-11f0-b898-0df219b8e170 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1755290492; x=1755895292; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=CEN/2XOrsEO0ZjOf5D7MPDTnV9rmV5trFiuPwf9NEvs=; b=ByY/ossxbKttZFjJAwXykNldMMrSfpFBb1HVfVoCOkmZBRf4+QQPSYcMA1YquZkjdE 6paMFf58ZNFsjXhek9+bIHJhqR+WiBnGVw1HF+xhnpnvcTqSNFux1DcQYmEj2BX2ApAD AlCPiZEy1pOg3ESdd4UczP57PVQRIwh00PhoQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755290492; x=1755895292; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=CEN/2XOrsEO0ZjOf5D7MPDTnV9rmV5trFiuPwf9NEvs=; b=F6vPsba4MkbYqV2oZtPPoS6yoTl05kdEZd6B0DPYUXaztaghsn0VN/Tkmfn6BDr3up zN9MXMgTVfmzDMJ/vHR3tgqNFs17eqnSTWHUVaBipBtq5yfBUn9YE3PVmowwxi28v/Rf 06dpHlzSSAQV/W/ewOrPgaYrp3sBj4SCQA4R2VWGwReYJYVrwBPmVbWDS2AbPy0onwI1 Bg81GqHSUhmR+bJ47TCY9jUoQfnr48QBgQxNkiOKlwuhbohUiss+jRBvIsqNbyePBqJZ M3KxpPIOIZEw0gE/o+NvbAruQqH+CknMTX3F//Usb55kQV9aqeydo06ECB5MFazYswlM tQzQ== X-Gm-Message-State: AOJu0YyGF8hZW1fP0zB/7jcF8qzLm80GwUBbEEER9UeCShWrIoOhnkcg H6KqlxHMlfAk7N4cAzmpj0zP3Z/zDtME0POBEgr3HyWkFasI/sLuTQB6M6clJ5DBu8LZH9bmlfp HmXQ9 X-Gm-Gg: ASbGnctxNooR3MwFJcy17La/rXweBWCDSfaugMNOO3NQ5yyHrm+UzXKWFf/J9oQUL8t c0ojiR5JqzJKMbo0OjUqaP0RByy2VoAWzmQVjTgFkVtlzVvWLsly509tEj3pXHNDvvJ9dH91pA0 LnJCZUwdKZMW1dlqP/mlXRSe1M/QThfHNTZ00CrJ3H7WlHfl72yn9q+qzdbdmpSSPnoZxMw0/84 6c+as0XvAv4+RJivtmCh2jQdQ0R+FVZ+Kdn+kzhumb+52r2f0dYfwk83LNfCcGMqlv8fDkQBV5y E8cLXRzn1I0cbUW8qCpIiTsrNDGIPuXco6nuPImiKt+IbCfgwbC09GHqlQNtA0ens3KLWMM+qWI P/hvVYq/vwGwOXN5QYyE1P2yB5FAH5kqp5XCZQltG+MasL8+diTji1VT/HuYrL1a0UO8PIb5E8i 4k X-Google-Smtp-Source: AGHT+IGWo66ukoW8MvWNvEHtUQjOhfM0bkel1B+NqYn/+qbSo2BCaaKx9/VegcKFb27gkUys+KKsfA== X-Received: by 2002:a05:6000:230b:b0:3b8:d081:3240 with SMTP id ffacd0b85a97d-3bb6636c7edmr2548031f8f.1.1755290492043; Fri, 15 Aug 2025 13:41:32 -0700 (PDT) From: Andrew Cooper To: Xen-devel Cc: Andrew Cooper , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Subject: [PATCH v2 15/16] x86/fsgsbase: Update fs/gs helpers to use wrmsrns() Date: Fri, 15 Aug 2025 21:41:16 +0100 Message-Id: <20250815204117.3312742-16-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250815204117.3312742-1-andrew.cooper3@citrix.com> References: <20250815204117.3312742-1-andrew.cooper3@citrix.com> 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: 1755290520660116600 ... and rdmsr() while here. Most of these accesses are in fastpaths and do not need serialising behavio= ur, but the write side is serialising on all Intel hardware as well as older AMD hardware. No functional change. Signed-off-by: Andrew Cooper --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 --- xen/arch/x86/domain.c | 10 +++++----- xen/arch/x86/hvm/vmx/vmx.c | 4 ++-- xen/arch/x86/include/asm/fsgsbase.h | 30 +++++++++-------------------- 3 files changed, 16 insertions(+), 28 deletions(-) diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c index 3015aac4adbc..2a9bb87729c8 100644 --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -1824,9 +1824,9 @@ static void load_segments(struct vcpu *n) } else { - wrmsrl(MSR_FS_BASE, n->arch.pv.fs_base); - wrmsrl(MSR_GS_BASE, gsb); - wrmsrl(MSR_SHADOW_GS_BASE, gss); + wrmsrns(MSR_FS_BASE, n->arch.pv.fs_base); + wrmsrns(MSR_GS_BASE, gsb); + wrmsrns(MSR_SHADOW_GS_BASE, gss); } } =20 @@ -1951,8 +1951,8 @@ static void save_segments(struct vcpu *v) } else { - rdmsrl(MSR_FS_BASE, fs_base); - rdmsrl(MSR_GS_BASE, gs_base); + fs_base =3D rdmsr(MSR_FS_BASE); + gs_base =3D rdmsr(MSR_GS_BASE); } =20 v->arch.pv.fs_base =3D fs_base; diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index f97a7746531a..9ba140c4811c 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -2733,8 +2733,8 @@ static uint64_t cf_check vmx_get_reg(struct vcpu *v, = unsigned int reg) case MSR_SHADOW_GS_BASE: if ( v !=3D curr ) return v->arch.hvm.vmx.shadow_gs; - rdmsrl(MSR_SHADOW_GS_BASE, val); - return val; + else + return rdmsr(MSR_SHADOW_GS_BASE); } =20 /* Logic which maybe requires remote VMCS acquisition. */ diff --git a/xen/arch/x86/include/asm/fsgsbase.h b/xen/arch/x86/include/asm= /fsgsbase.h index 90d116f3bb54..7a0b623cca8f 100644 --- a/xen/arch/x86/include/asm/fsgsbase.h +++ b/xen/arch/x86/include/asm/fsgsbase.h @@ -63,38 +63,26 @@ static inline void __wrgskern(unsigned long base) =20 static inline unsigned long read_fs_base(void) { - unsigned long base; - if ( read_cr4() & X86_CR4_FSGSBASE ) return __rdfsbase(); - - rdmsrl(MSR_FS_BASE, base); - - return base; + else + return rdmsr(MSR_FS_BASE); } =20 static inline unsigned long read_gs_base(void) { - unsigned long base; - if ( read_cr4() & X86_CR4_FSGSBASE ) return __rdgsbase(); - - rdmsrl(MSR_GS_BASE, base); - - return base; + else + return rdmsr(MSR_GS_BASE); } =20 static inline unsigned long read_gs_shadow(void) { - unsigned long base; - if ( read_cr4() & X86_CR4_FSGSBASE ) return __rdgskern(); - - rdmsrl(MSR_SHADOW_GS_BASE, base); - - return base; + else + return rdmsr(MSR_SHADOW_GS_BASE); } =20 static inline void write_fs_base(unsigned long base) @@ -102,7 +90,7 @@ static inline void write_fs_base(unsigned long base) if ( read_cr4() & X86_CR4_FSGSBASE ) __wrfsbase(base); else - wrmsrl(MSR_FS_BASE, base); + wrmsrns(MSR_FS_BASE, base); } =20 static inline void write_gs_base(unsigned long base) @@ -110,7 +98,7 @@ static inline void write_gs_base(unsigned long base) if ( read_cr4() & X86_CR4_FSGSBASE ) __wrgsbase(base); else - wrmsrl(MSR_GS_BASE, base); + wrmsrns(MSR_GS_BASE, base); } =20 static inline void write_gs_shadow(unsigned long base) @@ -118,7 +106,7 @@ static inline void write_gs_shadow(unsigned long base) if ( read_cr4() & X86_CR4_FSGSBASE ) __wrgskern(base); else - wrmsrl(MSR_SHADOW_GS_BASE, base); + wrmsrns(MSR_SHADOW_GS_BASE, base); } =20 #endif /* X86_FSGSBASE_H */ --=20 2.39.5