[U-Boot] [PATCH 097/126] x86: Add support for newer CAR schemes

Simon Glass sjg at chromium.org
Wed Sep 25 14:57:21 UTC 2019


Newer Intel SoCs have different ways of setting up cache-as-ram (CAR).
Add support for these along with suitable configuration options.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 arch/x86/Kconfig                        |  16 +
 arch/x86/cpu/intel_common/Kconfig       |  18 +
 arch/x86/cpu/intel_common/Makefile      |   8 +
 arch/x86/cpu/intel_common/car2.S        | 490 ++++++++++++++++++++++++
 arch/x86/cpu/intel_common/car2_uninit.S |  87 +++++
 5 files changed, 619 insertions(+)
 create mode 100644 arch/x86/cpu/intel_common/Kconfig
 create mode 100644 arch/x86/cpu/intel_common/car2.S
 create mode 100644 arch/x86/cpu/intel_common/car2_uninit.S

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 556e26080de..e34c71ec4cb 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -876,4 +876,20 @@ config HIGH_TABLE_SIZE
 	  Increse it if the default size does not fit the board's needs.
 	  This is most likely due to a large ACPI DSDT table is used.
 
+config INTEL_CAR_CQOS
+	bool "Support Intel Cache Quality of Service"
+	help
+	  Cache Quality of Service allows more fine-grained control of cache
+	  usage. As result, it is possible to set up a portion of L2 cache for
+	  CAR and use the remainder for actual caching.
+
+#
+# Each bit in QOS mask controls this many bytes. This is calculated as:
+# (CACHE_WAYS / CACHE_BITS_PER_MASK) * CACHE_LINE_SIZE * CACHE_SETS
+#
+config CACHE_QOS_SIZE_PER_BIT
+	hex
+	depends on INTEL_CAR_CQOS
+	default 0x20000 # 128 KB
+
 endmenu
diff --git a/arch/x86/cpu/intel_common/Kconfig b/arch/x86/cpu/intel_common/Kconfig
new file mode 100644
index 00000000000..a4f46b1108b
--- /dev/null
+++ b/arch/x86/cpu/intel_common/Kconfig
@@ -0,0 +1,18 @@
+config INTEL_PMC
+	bool "Intel Power-management Controller"
+	select POWER_MGR
+	help
+	  Enable support for the common Intel power-management controller which
+	  provides features including checking whether the system started from
+	  resume, powering off the system and enabling/disabling the reset
+	  mechanism.
+
+config SPL_INTEL_PMC
+	bool "Intel Power-management Controller in SPL"
+	default y if SPL && INTEL_PMC
+	select SPL_POWER_MGR
+	help
+	  Enable support for the common Intel power-management controller which
+	  provides features including checking whether the system started from
+	  resume, powering off the system and enabling/disabling the reset
+	  mechanism.
diff --git a/arch/x86/cpu/intel_common/Makefile b/arch/x86/cpu/intel_common/Makefile
index 2de567dd9fe..f620747a7d2 100644
--- a/arch/x86/cpu/intel_common/Makefile
+++ b/arch/x86/cpu/intel_common/Makefile
@@ -8,6 +8,14 @@ obj-$(CONFIG_$(SPL_TPL_)X86_32BIT_INIT) += me_status.o
 obj-$(CONFIG_$(SPL_TPL_)X86_32BIT_INIT) += report_platform.o
 obj-$(CONFIG_$(SPL_TPL_)X86_32BIT_INIT) += mrc.o
 endif
+
+ifdef CONFIG_FSP_VERSION2
+obj-$(CONFIG_TPL_BUILD) += car2.o
+ifndef CONFIG_SPL_BUILD
+obj-y += car2_uninit.o
+endif
+endif
+
 obj-y += cpu.o
 obj-$(CONFIG_SPI_FLASH_INTEL_FAST) += fast_spi.o
 obj-y += lpc.o
diff --git a/arch/x86/cpu/intel_common/car2.S b/arch/x86/cpu/intel_common/car2.S
new file mode 100644
index 00000000000..ac07fe5ea6a
--- /dev/null
+++ b/arch/x86/cpu/intel_common/car2.S
@@ -0,0 +1,490 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2015-2016 Intel Corp.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <config.h>
+#include <asm/msr-index.h>
+#include <asm/mtrr.h>
+#include <asm/post.h>
+#include <asm/processor-flags.h>
+
+#define KiB 1024
+
+.global car_init
+car_init:
+	post_code(0x20)
+
+	/*
+	 * Use the MTRR default type MSR as a proxy for detecting INIT#.
+	 * Reset the system if any known bits are set in that MSR. That is
+	 * an indication of the CPU not being properly reset.
+	 */
+check_for_clean_reset:
+	mov	$MTRR_DEF_TYPE_MSR, %ecx
+	rdmsr
+	and	$(MTRR_DEF_TYPE_EN | MTRR_DEF_TYPE_FIX_EN), %eax
+	cmp	$0, %eax
+	jz	no_reset
+	/* perform warm reset */
+	movw	$0xcf9, %dx
+	movb	$0x06, %al
+	outb	%al, %dx
+
+no_reset:
+	post_code(0x21)
+
+	/* Clear/disable fixed MTRRs */
+	mov	$fixed_mtrr_list_size, %ebx
+	xor	%eax, %eax
+	xor	%edx, %edx
+
+clear_fixed_mtrr:
+	add	$-2, %ebx
+	movzwl	fixed_mtrr_list(%ebx), %ecx
+	wrmsr
+	jnz	clear_fixed_mtrr
+
+	post_code(0x22)
+
+	/* Figure put how many MTRRs we have, and clear them out */
+	mov	$MTRR_CAP_MSR, %ecx
+	rdmsr
+	movzb	%al, %ebx		/* Number of variable MTRRs */
+	mov	$MTRR_PHYS_BASE_MSR(0), %ecx
+	xor	%eax, %eax
+	xor	%edx, %edx
+
+clear_var_mtrr:
+	wrmsr
+	inc	%ecx
+	wrmsr
+	inc	%ecx
+	dec	%ebx
+	jnz	clear_var_mtrr
+
+	post_code(0x23)
+
+	/* Configure default memory type to uncacheable (UC) */
+	mov	$MTRR_DEF_TYPE_MSR, %ecx
+	rdmsr
+	/* Clear enable bits and set default type to UC. */
+	and	$~(MTRR_DEF_TYPE_MASK | MTRR_DEF_TYPE_EN | \
+		 MTRR_DEF_TYPE_FIX_EN), %eax
+	wrmsr
+
+	/* Configure MTRR_PHYS_MASK_HIGH for proper addressing above 4GB
+	 * based on the physical address size supported for this processor
+	 * This is based on read from CPUID EAX = 080000008h, EAX bits [7:0]
+	 *
+	 * Examples:
+	 *  MTRR_PHYS_MASK_HIGH = 00000000Fh  For 36 bit addressing
+	 *  MTRR_PHYS_MASK_HIGH = 0000000FFh  For 40 bit addressing
+	 */
+
+	movl	$0x80000008, %eax 	/* Address sizes leaf */
+	cpuid
+	sub	$32, %al
+	movzx	%al, %eax
+	xorl	%esi, %esi
+	bts	%eax, %esi
+	dec	%esi			/* esi <- MTRR_PHYS_MASK_HIGH */
+
+	post_code(0x24)
+
+#if ((CONFIG_DCACHE_RAM_SIZE & (CONFIG_DCACHE_RAM_SIZE - 1)) == 0)
+	/* Configure CAR region as write-back (WB) */
+	mov	$MTRR_PHYS_BASE_MSR(0), %ecx
+	mov	$CONFIG_DCACHE_RAM_BASE, %eax
+	or	$MTRR_TYPE_WRBACK, %eax
+	xor	%edx,%edx
+	wrmsr
+
+	/* Configure the MTRR mask for the size region */
+	mov	$MTRR_PHYS_MASK(0), %ecx
+	mov	$CONFIG_DCACHE_RAM_SIZE, %eax	/* size mask */
+	dec	%eax
+	not	%eax
+	or	$MTRR_PHYS_MASK_VALID, %eax
+	movl	%esi, %edx	/* edx <- MTRR_PHYS_MASK_HIGH */
+	wrmsr
+#elif (CONFIG_DCACHE_RAM_SIZE == 768 * KiB) /* 768 KiB */
+	/* Configure CAR region as write-back (WB) */
+	mov	$MTRR_PHYS_BASE_MSR(0), %ecx
+	mov	$CONFIG_DCACHE_RAM_BASE, %eax
+	or	$MTRR_TYPE_WRBACK, %eax
+	xor	%edx,%edx
+	wrmsr
+
+	mov	$MTRR_PHYS_MASK_MSR(0), %ecx
+	mov	$(512 * KiB), %eax	/* size mask */
+	dec	%eax
+	not	%eax
+	or	$MTRR_PHYS_MASK_VALID, %eax
+	movl	%esi, %edx	/* edx <- MTRR_PHYS_MASK_HIGH */
+	wrmsr
+
+	mov	$MTRR_PHYS_BASE_MSR(1), %ecx
+	mov	$(CONFIG_DCACHE_RAM_BASE + 512 * KiB), %eax
+	or	$MTRR_TYPE_WRBACK, %eax
+	xor	%edx,%edx
+	wrmsr
+
+	mov	$MTRR_PHYS_MASK_MSR(1), %ecx
+	mov	$(256 * KiB), %eax	/* size mask */
+	dec	%eax
+	not	%eax
+	or	$MTRR_PHYS_MASK_VALID, %eax
+	movl	%esi, %edx	/* edx <- MTRR_PHYS_MASK_HIGH */
+	wrmsr
+#else
+#error "DCACHE_RAM_SIZE is not a power of 2 and setup code is missing"
+#endif
+	post_code(0x25)
+
+	/* start */
+/* 	mov	$0xffff80a8, %ebx */
+/* 	jmp	*%ebx */
+.globl _from_bb
+_from_bb:
+/* 	jmp	car_init_ret */
+	/* end */
+
+	/* Enable variable MTRRs */
+	mov	$MTRR_DEF_TYPE_MSR, %ecx
+	rdmsr
+	or	$MTRR_DEF_TYPE_EN, %eax
+	wrmsr
+
+	/* Enable caching */
+	mov	%cr0, %eax
+	and	$~(X86_CR0_CD | X86_CR0_NW), %eax
+	invd
+	mov	%eax, %cr0
+
+#if IS_ENABLED(CONFIG_INTEL_CAR_NEM)
+	jmp car_nem
+#elif IS_ENABLED(CONFIG_INTEL_CAR_CQOS)
+	jmp car_cqos
+#elif IS_ENABLED(CONFIG_INTEL_CAR_NEM_ENHANCED)
+	jmp car_nem_enhanced
+#else
+#error "No CAR mechanism selected:
+#endif
+	jmp	car_init_ret
+
+#if 0
+.global car_init_done
+car_init_done:
+
+	post_code(0x29)
+
+	/* Setup bootblock stack */
+	mov	$_car_stack_end, %esp
+
+	/* Need to align stack to 16 bytes at call instruction. Account for
+	   the two pushes below. */
+	andl	$0xfffffff0, %esp
+	sub	$8, %esp
+
+	/*push TSC value to stack*/
+	movd	%mm2, %eax
+	pushl	%eax	/* tsc[63:32] */
+	movd	%mm1, %eax
+	pushl	%eax 	/* tsc[31:0] */
+
+before_carstage:
+	post_code(0x2A)
+
+	call	bootblock_c_entry
+	/* Never reached */
+#endif
+
+fixed_mtrr_list:
+	.word	MTRR_FIX_64K_00000_MSR
+	.word	MTRR_FIX_16K_80000_MSR
+	.word	MTRR_FIX_16K_A0000_MSR
+	.word	MTRR_FIX_4K_C0000_MSR
+	.word	MTRR_FIX_4K_C8000_MSR
+	.word	MTRR_FIX_4K_D0000_MSR
+	.word	MTRR_FIX_4K_D8000_MSR
+	.word	MTRR_FIX_4K_E0000_MSR
+	.word	MTRR_FIX_4K_E8000_MSR
+	.word	MTRR_FIX_4K_F0000_MSR
+	.word	MTRR_FIX_4K_F8000_MSR
+fixed_mtrr_list_size = . - fixed_mtrr_list
+
+#if IS_ENABLED(CONFIG_INTEL_CAR_NEM)
+.global car_nem
+car_nem:
+	/* Disable cache eviction (setup stage) */
+	mov	$MSR_EVICT_CTL, %ecx
+	rdmsr
+	or	$0x1, %eax
+	wrmsr
+
+	post_code(0x26)
+
+	/* Clear the cache memory region. This will also fill up the cache */
+	movl	$CONFIG_DCACHE_RAM_BASE, %edi
+	movl	$CONFIG_DCACHE_RAM_SIZE, %ecx
+	shr	$0x02, %ecx
+	xor	%eax, %eax
+	cld
+	rep	stosl
+
+	post_code(0x27)
+
+	/* Disable cache eviction (run stage) */
+	mov	$MSR_EVICT_CTL, %ecx
+	rdmsr
+	or	$0x2, %eax
+	wrmsr
+
+	post_code(0x28)
+
+	jmp car_init_done
+
+#elif IS_ENABLED(CONFIG_INTEL_CAR_CQOS)
+.global car_cqos
+car_cqos:
+	/*
+	 * Create CBM_LEN_MASK based on CBM_LEN
+	 * Get CPUID.(EAX=10H, ECX=2H):EAX.CBM_LEN[bits 4:0]
+	 */
+	mov $0x10, %eax
+	mov $0x2,  %ecx
+	cpuid
+	and $0x1F, %eax
+	add $1, %al
+
+	mov $1, %ebx
+	mov %al, %cl
+	shl %cl, %ebx
+	sub $1, %ebx
+
+	/* Store the CBM_LEN_MASK in mm3 for later use. */
+	movd %ebx, %mm3
+
+	/*
+	 * Disable both L1 and L2 prefetcher. For yet-to-understood reason,
+	 * prefetchers slow down filling cache with rep stos in CQOS mode.
+	 */
+	mov	$MSR_PREFETCH_CTL, %ecx
+	rdmsr
+	or	$(PREFETCH_L1_DISABLE | PREFETCH_L2_DISABLE), %eax
+	wrmsr
+
+#if (CONFIG_DCACHE_RAM_SIZE == CONFIG_L2_CACHE_SIZE)
+/*
+ * If CAR size is set to full L2 size, mask is calculated as all-zeros.
+ * This is not supported by the CPU/uCode.
+ */
+#error "CQOS CAR may not use whole L2 cache area"
+#endif
+
+	/* Calculate how many bits to be used for CAR */
+	xor	%edx, %edx
+	mov	$CONFIG_DCACHE_RAM_SIZE, %eax	/* dividend */
+	mov	$CONFIG_CACHE_QOS_SIZE_PER_BIT, %ecx	/* divisor */
+	div	%ecx		/* result is in eax */
+	mov	%eax, %ecx	/* save to ecx */
+	mov	$1, %ebx
+	shl	%cl, %ebx
+	sub	$1, %ebx	/* resulting mask is is in ebx */
+
+	/* Set this mask for initial cache fill */
+	mov	$MSR_L2_QOS_MASK(0), %ecx
+	rdmsr
+	mov	%ebx, %eax
+	wrmsr
+
+	/* Set CLOS selector to 0 */
+	mov	$MSR_IA32_PQR_ASSOC, %ecx
+	rdmsr
+	and	$~MSR_IA32_PQR_ASSOC_MASK, %edx	/* select mask 0 */
+	wrmsr
+
+	/* We will need to block CAR region from evicts */
+	mov	$MSR_L2_QOS_MASK(1), %ecx
+	rdmsr
+	/* Invert bits that are to be used for cache */
+	mov	%ebx, %eax
+	xor	$~0, %eax			/* invert 32 bits */
+
+	/*
+	 * Use CBM_LEN_MASK stored in mm3 to set bits based on Capacity Bit
+	 * Mask Length.
+	 */
+	movd	%mm3, %ebx
+	and	%ebx, %eax
+	wrmsr
+
+	post_code(0x26)
+
+	/* Clear the cache memory region. This will also fill up the cache */
+	movl	$CONFIG_DCACHE_RAM_BASE, %edi
+	movl	$CONFIG_DCACHE_RAM_SIZE, %ecx
+	shr	$0x02, %ecx
+	xor	%eax, %eax
+	cld
+	rep	stosl
+
+	post_code(0x27)
+
+	/* Cache is populated. Use mask 1 that will block evicts */
+	mov	$MSR_IA32_PQR_ASSOC, %ecx
+	rdmsr
+	and	$~MSR_IA32_PQR_ASSOC_MASK, %edx	/* clear index bits first */
+	or	$1, %edx			/* select mask 1 */
+	wrmsr
+
+	/* Enable prefetchers */
+	mov	$MSR_PREFETCH_CTL, %ecx
+	rdmsr
+	and	$~(PREFETCH_L1_DISABLE | PREFETCH_L2_DISABLE), %eax
+	wrmsr
+
+	post_code(0x28)
+
+/* 	jmp car_init_done */
+	jmp	car_init_ret
+
+#elif IS_ENABLED(CONFIG_INTEL_CAR_NEM_ENHANCED)
+.global car_nem_enhanced
+car_nem_enhanced:
+	/* Disable cache eviction (setup stage) */
+	mov	$MSR_EVICT_CTL, %ecx
+	rdmsr
+	or	$0x1, %eax
+	wrmsr
+	post_code(0x26)
+
+	/* Create n-way set associativity of cache */
+	xorl	%edi, %edi
+find_llc_subleaf:
+	movl	%edi, %ecx
+	movl	$0x04, %eax
+	cpuid
+	inc	%edi
+	and	$0xe0, %al	/* EAX[7:5] = Cache Level */
+	cmp	$0x60, %al	/* Check to see if it is LLC */
+	jnz	find_llc_subleaf
+
+	/*
+	 * Set MSR 0xC91 IA32_L3_MASK_! = 0xE/0xFE/0xFFE/0xFFFE
+	 * for 4/8/16 way of LLC
+	*/
+	shr	$22, %ebx
+	inc	%ebx
+	/* Calculate n-way associativity of LLC */
+	mov	%bl, %cl
+
+	/*
+	 * Maximizing RO cacheability while locking in the CAR to a
+	 * single way since that particular way won't be victim candidate
+	 * for evictions.
+	 * This has been done after programing LLC_WAY_MASK_1 MSR
+	 * with desired LLC way as mentioned below.
+	 *
+	 * Hence create Code and Data Size as per request
+	 * Code Size (RO) : Up to 16M
+	 * Data Size (RW) : Up to 256K
+	 */
+	movl	$0x01, %eax
+	/*
+	 * LLC Ways -> LLC_WAY_MASK_1:
+	 *  4: 0x000E
+	 *  8: 0x00FE
+	 * 12: 0x0FFE
+	 * 16: 0xFFFE
+	 *
+	 * These MSRs contain one bit per each way of LLC
+	 * - If this bit is '0' - the way is protected from eviction
+	 * - If this bit is '1' - the way is not protected from eviction
+	 */
+	shl	%cl, %eax
+	subl	$0x02, %eax
+	movl	$MSR_IA32_L3_MASK_1, %ecx
+	xorl	%edx, %edx
+	wrmsr
+	/*
+	 * Set MSR 0xC92 IA32_L3_MASK_2 = 0x1
+	 *
+	 * For SKL SOC, data size remains 256K consistently.
+	 * Hence, creating 1-way associative cache for Data
+	*/
+	mov	$MSR_IA32_L3_MASK_2, %ecx
+	mov	$0x01, %eax
+	xorl	%edx, %edx
+	wrmsr
+	/*
+	 * Set MSR_IA32_PQR_ASSOC = 0x02
+	 *
+	 * Possible values:
+	 * 0: Default value, no way mask should be applied
+	 * 1: Apply way mask 1 to LLC
+	 * 2: Apply way mask 2 to LLC
+	 * 3: Shouldn't be use in NEM Mode
+	 */
+	movl	$MSR_IA32_PQR_ASSOC, %ecx
+	movl	$0x02, %eax
+	xorl	%edx, %edx
+	wrmsr
+
+	movl	$CONFIG_DCACHE_RAM_BASE, %edi
+	movl	$CONFIG_DCACHE_RAM_SIZE, %ecx
+	shr	$0x02, %ecx
+	xor	%eax, %eax
+	cld
+	rep	stosl
+	/*
+	 * Set MSR_IA32_PQR_ASSOC = 0x01
+	 * At this stage we apply LLC_WAY_MASK_1 to the cache.
+	 * i.e. way 0 is protected from eviction.
+	*/
+	movl	$MSR_IA32_PQR_ASSOC, %ecx
+	movl	$0x01, %eax
+	xorl	%edx, %edx
+	wrmsr
+
+	post_code(0x27)
+	/*
+	 * Enable No-Eviction Mode Run State by setting
+	 * NO_EVICT_MODE MSR 2E0h bit [1] = '1'.
+	 */
+
+	movl	$MSR_EVICT_CTL, %ecx
+	rdmsr
+	orl	$0x02, %eax
+	wrmsr
+
+	post_code(0x28)
+
+	jmp car_init_done
+#endif
+
+#if CONFIG_IS_ENABLED(X86_16BIT_INIT)
+_dt_ucode_base_size:
+	/* These next two fields are filled in by binman */
+.globl ucode_base
+ucode_base:	/* Declared in microcode.h */
+	.long	0			/* microcode base */
+.globl ucode_size
+ucode_size:	/* Declared in microcode.h */
+	.long	0			/* microcode size */
+	.long	CONFIG_SYS_MONITOR_BASE	/* code region base */
+	.long	CONFIG_SYS_MONITOR_LEN	/* code region size */
+#endif
diff --git a/arch/x86/cpu/intel_common/car2_uninit.S b/arch/x86/cpu/intel_common/car2_uninit.S
new file mode 100644
index 00000000000..4797ac04279
--- /dev/null
+++ b/arch/x86/cpu/intel_common/car2_uninit.S
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2017 Intel Corp.
+ * Copyright 2019 Google LLC
+ * Taken from coreboot file exit_car.S
+ */
+
+#include <config.h>
+#include <asm/msr-index.h>
+#include <asm/mtrr.h>
+
+.text
+.global car_uninit
+car_uninit:
+
+	/*
+	 * Retrieve return address from stack as it will get trashed below if
+	 * execution is utilizing the cache-as-ram stack.
+	 */
+	pop	%ebx
+
+	/* Disable MTRRs. */
+	mov	$(MTRR_DEF_TYPE_MSR), %ecx
+	rdmsr
+	and	$(~(MTRR_DEF_TYPE_EN | MTRR_DEF_TYPE_FIX_EN)), %eax
+	wrmsr
+
+#ifdef CONFIG_INTEL_CAR_NEM
+.global car_nem_teardown
+car_nem_teardown:
+
+	/* invalidate cache contents. */
+	invd
+
+	/* Knock down bit 1 then bit 0 of NEM control not combining steps. */
+	mov	$(MSR_EVICT_CTL), %ecx
+	rdmsr
+	and	$(~(1 << 1)), %eax
+	wrmsr
+	and	$(~(1 << 0)), %eax
+	wrmsr
+
+#elif IS_ENABLED(CONFIG_INTEL_CAR_CQOS)
+.global car_cqos_teardown
+car_cqos_teardown:
+
+	/* Go back to all-evicting mode, set both masks to all-1s */
+	mov	$MSR_L2_QOS_MASK(0), %ecx
+	rdmsr
+	mov	$~0, %al
+	wrmsr
+
+	mov	$MSR_L2_QOS_MASK(1), %ecx
+	rdmsr
+	mov	$~0, %al
+	wrmsr
+
+	/* Reset CLOS selector to 0 */
+	mov	$MSR_IA32_PQR_ASSOC, %ecx
+	rdmsr
+	and	$~MSR_IA32_PQR_ASSOC_MASK, %edx
+	wrmsr
+
+#elif IS_ENABLED(CONFIG_INTEL_CAR_NEM_ENHANCED)
+.global car_nem_enhanced_teardown
+car_nem_enhanced_teardown:
+
+	/* invalidate cache contents. */
+	invd
+
+	/* Knock down bit 1 then bit 0 of NEM control not combining steps. */
+	mov	$(MSR_EVICT_CTL), %ecx
+	rdmsr
+	and	$(~(1 << 1)), %eax
+	wrmsr
+	and	$(~(1 << 0)), %eax
+	wrmsr
+
+	/* Reset CLOS selector to 0 */
+	mov	$IA32_PQR_ASSOC, %ecx
+	rdmsr
+	and	$~IA32_PQR_ASSOC_MASK, %edx
+	wrmsr
+#endif
+
+	/* Return to caller. */
+	jmp	*%ebx
-- 
2.23.0.444.g18eeb5a265-goog



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