From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga06.intel.com (mga06.intel.com []) by mx.groups.io with SMTP id smtpd.web08.3799.1615865640867281038 for ; Mon, 15 Mar 2021 20:34:05 -0700 Authentication-Results: mx.groups.io; dkim=missing; spf=fail (domain: intel.com, ip: , mailfrom: ray.ni@intel.com) IronPort-SDR: wEz4WkUkalIOe80ktJXDYvmu24f+9e0xVNP9xiW51HhG1cK10vD7CvGCs9FgOUmw06uIbnN49t ZMNUeA9nKBhg== X-IronPort-AV: E=McAfee;i="6000,8403,9924"; a="250558003" X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="250558003" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Mar 2021 20:34:05 -0700 IronPort-SDR: b1bzIkxtuHQnyO1Jw1KMpFRjZIpjPoETd3lN7L7XpI4u3ucpC6ohOuymjWRWRBZOTyYW1Ci8K7 bK9INailnoIw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="605098151" Received: from ray-dev.ccr.corp.intel.com ([10.239.158.87]) by fmsmga005.fm.intel.com with ESMTP; 15 Mar 2021 20:34:01 -0700 From: "Ni, Ray" To: devel@edk2.groups.io Cc: Eric Dong , Laszlo Ersek , Rahul Kumar Subject: [PATCH 2/2] UefiCpuPkg/CpuDxe: Guarantee GDT is below 4GB Date: Tue, 16 Mar 2021 11:33:50 +0800 Message-Id: <20210316033350.2026-3-ray.ni@intel.com> X-Mailer: git-send-email 2.27.0.windows.1 In-Reply-To: <20210316033350.2026-1-ray.ni@intel.com> References: <20210316033350.2026-1-ray.ni@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3D3233 GDT needs to be allocated below 4GB in 64bit environment because AP needs it for entering to protected mode. CPU running in big real mode cannot access above 4GB GDT. But CpuDxe driver contains below code: gdt =3D AllocateRuntimePool (sizeof (GdtTemplate) + 8); ..... gdtPtr.Base =3D (UINT32)(UINTN)(VOID*) gdt; The AllocateRuntimePool() may allocate memory above 4GB. Thus, we cannot use AllocateRuntimePool (), instead, we should use AllocatePages() to make sure GDT is below 4GB space. Signed-off-by: Ray Ni Cc: Eric Dong Cc: Laszlo Ersek Cc: Rahul Kumar --- UefiCpuPkg/CpuDxe/CpuGdt.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/UefiCpuPkg/CpuDxe/CpuGdt.c b/UefiCpuPkg/CpuDxe/CpuGdt.c index 322ce87142..98d5551702 100644 --- a/UefiCpuPkg/CpuDxe/CpuGdt.c +++ b/UefiCpuPkg/CpuDxe/CpuGdt.c @@ -124,15 +124,26 @@ InitGlobalDescriptorTable ( VOID=0D )=0D {=0D + EFI_STATUS Status;=0D GDT_ENTRIES *Gdt;=0D IA32_DESCRIPTOR Gdtr;=0D + EFI_PHYSICAL_ADDRESS Memory;=0D =0D //=0D - // Allocate Runtime Data for the GDT=0D - //=0D - Gdt =3D AllocateRuntimePool (sizeof (gGdtTemplate) + 8);=0D - ASSERT (Gdt !=3D NULL);=0D - Gdt =3D ALIGN_POINTER (Gdt, 8);=0D + // Allocate Runtime Data below 4GB for the GDT=0D + // AP uses the same GDT when it's waken up from real mode so=0D + // the GDT needs to be below 4GB.=0D + //=0D + Memory =3D SIZE_4GB - 1;=0D + Status =3D gBS->AllocatePages (=0D + AllocateMaxAddress,=0D + EfiRuntimeServicesData,=0D + EFI_SIZE_TO_PAGES (sizeof (gGdtTemplate)),=0D + &Memory=0D + );=0D + ASSERT_EFI_ERROR (Status);=0D + ASSERT ((Memory !=3D 0) && (Memory < SIZE_4GB));=0D + Gdt =3D (GDT_ENTRIES *) (UINTN) Memory;=0D =0D //=0D // Initialize all GDT entries=0D --=20 2.27.0.windows.1