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From: Kuppuswamy Sathyanarayanan  <sathyanarayanan.kuppuswamy@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>,
	Kirill Shutemov <kirill.shutemov@linux.intel.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	Sean Christopherson <seanjc@google.com>,
	linux-kernel@vger.kernel.org,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Kuppuswamy Sathyanarayanan 
	<sathyanarayanan.kuppuswamy@linux.intel.com>
Subject: [RFC v1 17/26] x86/boot: Avoid unnecessary #VE during boot process
Date: Fri,  5 Feb 2021 15:38:34 -0800	[thread overview]
Message-ID: <fde86d8f8c611abea1672d8ece8446db381d8214.1612563142.git.sathyanarayanan.kuppuswamy@linux.intel.com> (raw)
In-Reply-To: <cover.1612563142.git.sathyanarayanan.kuppuswamy@linux.intel.com>

From: Sean Christopherson <sean.j.christopherson@intel.com>

Skip writing EFER during secondary_startup_64() if the current value is
also the desired value. This avoids a #VE when running as a TDX guest,
as the TDX-Module does not allow writes to EFER (even when writing the
current, fixed value).

Also, preserve CR4.MCE instead of clearing it during boot to avoid a #VE
when running as a TDX guest. The TDX-Module (effectively part of the
hypervisor) requires CR4.MCE to be set at all times and injects a #VE
if the guest attempts to clear CR4.MCE.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
 arch/x86/boot/compressed/head_64.S |  5 ++++-
 arch/x86/kernel/head_64.S          | 13 +++++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 37c2f37d4a0d..2d79e5f97360 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -622,7 +622,10 @@ SYM_CODE_START(trampoline_32bit_src)
 	popl	%ecx
 
 	/* Enable PAE and LA57 (if required) paging modes */
-	movl	$X86_CR4_PAE, %eax
+	movl	%cr4, %eax
+	/* Clearing CR4.MCE will #VE on TDX guests.  Leave it alone. */
+	andl	$X86_CR4_MCE, %eax
+	orl	$X86_CR4_PAE, %eax
 	testl	%edx, %edx
 	jz	1f
 	orl	$X86_CR4_LA57, %eax
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 04bddaaba8e2..92c77cf75542 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -141,7 +141,10 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
 1:
 
 	/* Enable PAE mode, PGE and LA57 */
-	movl	$(X86_CR4_PAE | X86_CR4_PGE), %ecx
+	movq	%cr4, %rcx
+	/* Clearing CR4.MCE will #VE on TDX guests.  Leave it alone. */
+	andl	$X86_CR4_MCE, %ecx
+	orl	$(X86_CR4_PAE | X86_CR4_PGE), %ecx
 #ifdef CONFIG_X86_5LEVEL
 	testl	$1, __pgtable_l5_enabled(%rip)
 	jz	1f
@@ -229,13 +232,19 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
 	/* Setup EFER (Extended Feature Enable Register) */
 	movl	$MSR_EFER, %ecx
 	rdmsr
+	movl    %eax, %edx
 	btsl	$_EFER_SCE, %eax	/* Enable System Call */
 	btl	$20,%edi		/* No Execute supported? */
 	jnc     1f
 	btsl	$_EFER_NX, %eax
 	btsq	$_PAGE_BIT_NX,early_pmd_flags(%rip)
-1:	wrmsr				/* Make changes effective */
 
+	/* Skip the WRMSR if the current value matches the desired value. */
+1:	cmpl	%edx, %eax
+	je	1f
+	xor	%edx, %edx
+	wrmsr				/* Make changes effective */
+1:
 	/* Setup cr0 */
 	movl	$CR0_STATE, %eax
 	/* Make changes effective */
-- 
2.25.1


  parent reply	other threads:[~2021-02-06  4:37 UTC|newest]

Thread overview: 161+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-06  3:02 Test Email sathyanarayanan.kuppuswamy
2021-02-05 23:38 ` [RFC v1 00/26] Add TDX Guest Support Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 01/26] x86/paravirt: Introduce CONFIG_PARAVIRT_XL Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 02/26] x86/cpufeatures: Add TDX Guest CPU feature Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 03/26] x86/cpufeatures: Add is_tdx_guest() interface Kuppuswamy Sathyanarayanan
2021-04-01 21:08   ` Dave Hansen
2021-04-01 21:15     ` Kuppuswamy, Sathyanarayanan
2021-04-01 21:19       ` Dave Hansen
2021-04-01 22:25         ` Kuppuswamy, Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 04/26] x86/tdx: Get TD execution environment information via TDINFO Kuppuswamy Sathyanarayanan
2021-02-08 10:00   ` Peter Zijlstra
2021-02-08 19:10     ` Kuppuswamy, Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 05/26] x86/traps: Add #VE support for TDX guest Kuppuswamy Sathyanarayanan
2021-02-08 10:20   ` Peter Zijlstra
2021-02-08 16:23     ` Andi Kleen
2021-02-08 16:33       ` Peter Zijlstra
2021-02-08 16:46         ` Sean Christopherson
2021-02-08 16:59           ` Peter Zijlstra
2021-02-08 19:05             ` Kuppuswamy, Sathyanarayanan
2021-02-08 16:46         ` Andi Kleen
2021-02-12 19:20   ` Dave Hansen
2021-02-12 19:47   ` Andy Lutomirski
2021-02-12 20:06     ` Sean Christopherson
2021-02-12 20:17       ` Dave Hansen
2021-02-12 20:37         ` Sean Christopherson
2021-02-12 20:46           ` Dave Hansen
2021-02-12 20:54             ` Sean Christopherson
2021-02-12 21:06               ` Dave Hansen
2021-02-12 21:37                 ` Sean Christopherson
2021-02-12 21:47                   ` Andy Lutomirski
2021-02-12 21:48                     ` Dave Hansen
2021-02-14 19:33                       ` Andi Kleen
2021-02-14 19:54                         ` Andy Lutomirski
2021-02-12 20:20       ` Andy Lutomirski
2021-02-12 20:44         ` Sean Christopherson
2021-02-05 23:38 ` [RFC v1 06/26] x86/tdx: Add HLT " Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 07/26] x86/tdx: Wire up KVM hypercalls Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 08/26] x86/tdx: Add MSR support for TDX guest Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 09/26] x86/tdx: Handle CPUID via #VE Kuppuswamy Sathyanarayanan
2021-02-05 23:42   ` Andy Lutomirski
2021-02-07 14:13     ` Kirill A. Shutemov
2021-02-07 16:01       ` Dave Hansen
2021-02-07 20:29         ` Kirill A. Shutemov
2021-02-07 22:31           ` Dave Hansen
2021-02-07 22:45             ` Andy Lutomirski
2021-02-08 17:10               ` Sean Christopherson
2021-02-08 17:35                 ` Andy Lutomirski
2021-02-08 17:47                   ` Sean Christopherson
2021-03-18 21:30               ` [PATCH v1 1/1] x86/tdx: Add tdcall() and tdvmcall() helper functions Kuppuswamy Sathyanarayanan
2021-03-19 16:55                 ` Sean Christopherson
2021-03-19 17:42                   ` Kuppuswamy, Sathyanarayanan
2021-03-19 18:22                     ` Dave Hansen
2021-03-19 19:58                       ` Kuppuswamy, Sathyanarayanan
2021-03-26 23:38                         ` [PATCH v2 1/1] x86/tdx: Add __tdcall() and __tdvmcall() " Kuppuswamy Sathyanarayanan
2021-04-20 17:36                           ` Dave Hansen
2021-04-20 19:20                             ` Kuppuswamy, Sathyanarayanan
2021-04-20 19:59                               ` Dave Hansen
2021-04-20 23:12                                 ` Kuppuswamy, Sathyanarayanan
2021-04-20 23:42                                   ` Dave Hansen
2021-04-23  1:09                                     ` Kuppuswamy, Sathyanarayanan
2021-04-23  1:21                                       ` Dave Hansen
2021-04-23  1:35                                         ` Andi Kleen
2021-04-23 15:15                                           ` Sean Christopherson
2021-04-23 15:28                                             ` Dan Williams
2021-04-23 15:38                                               ` Andi Kleen
2021-04-23 15:50                                               ` Sean Christopherson
2021-04-23 15:47                                             ` Andi Kleen
2021-04-23 18:18                                             ` Kuppuswamy, Sathyanarayanan
2021-04-20 23:53                                   ` Dan Williams
2021-04-20 23:59                                     ` Kuppuswamy, Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 10/26] x86/io: Allow to override inX() and outX() implementation Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 11/26] x86/tdx: Handle port I/O Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 12/26] x86/tdx: Handle in-kernel MMIO Kuppuswamy Sathyanarayanan
2021-04-01 19:56   ` Dave Hansen
2021-04-01 22:26     ` Sean Christopherson
2021-04-01 22:53       ` Dave Hansen
2021-02-05 23:38 ` [RFC v1 13/26] x86/tdx: Handle MWAIT, MONITOR and WBINVD Kuppuswamy Sathyanarayanan
2021-02-05 23:43   ` Andy Lutomirski
2021-02-05 23:54     ` Kuppuswamy, Sathyanarayanan
2021-02-06  1:05       ` Andy Lutomirski
2021-03-27  0:18         ` [PATCH v1 1/1] " Kuppuswamy Sathyanarayanan
2021-03-27  2:40           ` Andy Lutomirski
2021-03-27  3:40             ` Kuppuswamy, Sathyanarayanan
2021-03-27 16:03               ` Andy Lutomirski
2021-03-27 22:54                 ` [PATCH v2 " Kuppuswamy Sathyanarayanan
2021-03-29 17:14                   ` Dave Hansen
2021-03-29 21:55                     ` Kuppuswamy, Sathyanarayanan
2021-03-29 22:02                       ` Dave Hansen
2021-03-29 22:09                         ` Kuppuswamy, Sathyanarayanan
2021-03-29 22:12                           ` Dave Hansen
2021-03-29 22:42                             ` Kuppuswamy, Sathyanarayanan
2021-03-29 23:16                             ` [PATCH v3 " Kuppuswamy Sathyanarayanan
2021-03-29 23:23                               ` Andy Lutomirski
2021-03-29 23:37                                 ` Kuppuswamy, Sathyanarayanan
2021-03-29 23:42                                   ` Sean Christopherson
2021-03-29 23:58                                     ` Andy Lutomirski
2021-03-30  2:04                                       ` Andi Kleen
2021-03-30  2:58                                         ` Andy Lutomirski
2021-03-30 15:14                                           ` Sean Christopherson
2021-03-30 16:37                                             ` Andy Lutomirski
2021-03-30 16:57                                               ` Sean Christopherson
2021-04-07 15:24                                                 ` Andi Kleen
2021-03-31 21:09                                           ` [PATCH v4 " Kuppuswamy Sathyanarayanan
2021-03-31 21:49                                             ` Dave Hansen
2021-03-31 22:29                                               ` Kuppuswamy, Sathyanarayanan
2021-03-31 21:53                                             ` Sean Christopherson
2021-03-31 22:00                                               ` Dave Hansen
2021-03-31 22:06                                                 ` Sean Christopherson
2021-03-31 22:11                                                   ` Dave Hansen
2021-03-31 22:28                                                     ` Kuppuswamy, Sathyanarayanan
2021-03-31 22:32                                                       ` Sean Christopherson
2021-03-31 22:34                                                       ` Dave Hansen
2021-04-01  3:28                                                         ` Andi Kleen
2021-04-01  3:46                                                           ` Dave Hansen
2021-04-01  4:24                                                             ` Andi Kleen
2021-04-01  4:51                                                               ` [PATCH v5 " Kuppuswamy Sathyanarayanan
2021-03-29 23:39                                 ` [PATCH v3 " Sean Christopherson
2021-03-29 23:38                               ` Dave Hansen
2021-03-30  4:56           ` [PATCH v1 " Xiaoyao Li
2021-03-30 15:00             ` Andi Kleen
2021-03-30 15:10               ` Dave Hansen
2021-03-30 17:02                 ` Kuppuswamy, Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 14/26] ACPI: tables: Add multiprocessor wake-up support Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 15/26] x86/boot: Add a trampoline for APs booting in 64-bit mode Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 16/26] x86/boot: Avoid #VE during compressed boot for TDX platforms Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` Kuppuswamy Sathyanarayanan [this message]
2021-02-05 23:38 ` [RFC v1 18/26] x86/topology: Disable CPU hotplug support " Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 19/26] x86/tdx: Forcefully disable legacy PIC for TDX guests Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 20/26] x86/tdx: Introduce INTEL_TDX_GUEST config option Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 21/26] x86/mm: Move force_dma_unencrypted() to common code Kuppuswamy Sathyanarayanan
2021-04-01 20:06   ` Dave Hansen
2021-04-06 15:37     ` Kirill A. Shutemov
2021-04-06 16:11       ` Dave Hansen
2021-04-06 16:37         ` Kirill A. Shutemov
2021-02-05 23:38 ` [RFC v1 22/26] x86/tdx: Exclude Shared bit from __PHYSICAL_MASK Kuppuswamy Sathyanarayanan
2021-04-01 20:13   ` Dave Hansen
2021-04-06 15:54     ` Kirill A. Shutemov
2021-04-06 16:12       ` Dave Hansen
2021-02-05 23:38 ` [RFC v1 23/26] x86/tdx: Make pages shared in ioremap() Kuppuswamy Sathyanarayanan
2021-04-01 20:26   ` Dave Hansen
2021-04-06 16:00     ` Kirill A. Shutemov
2021-04-06 16:14       ` Dave Hansen
2021-02-05 23:38 ` [RFC v1 24/26] x86/tdx: Add helper to do MapGPA TDVMALL Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 25/26] x86/tdx: Make DMA pages shared Kuppuswamy Sathyanarayanan
2021-04-01 21:01   ` Dave Hansen
2021-04-06 16:31     ` Kirill A. Shutemov
2021-04-06 16:38       ` Dave Hansen
2021-04-06 17:16         ` Sean Christopherson
2021-02-05 23:38 ` [RFC v1 26/26] x86/kvm: Use bounce buffers for TD guest Kuppuswamy Sathyanarayanan
2021-04-01 21:17   ` Dave Hansen
2021-02-06  3:04 ` Test Email sathyanarayanan.kuppuswamy
2021-02-06  6:24 ` [RFC v1 00/26] Add TDX Guest Support sathyanarayanan.kuppuswamy
2021-03-31 21:38 ` Kuppuswamy, Sathyanarayanan
2021-04-02  0:02 ` Dave Hansen
2021-04-02  2:48   ` Andi Kleen
2021-04-02 15:27     ` Dave Hansen
2021-04-02 21:32       ` Andi Kleen
2021-04-03 16:26         ` Dave Hansen
2021-04-03 17:28           ` Andi Kleen
2021-04-04 15:02 ` Dave Hansen
2021-04-12 17:24   ` Dan Williams

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