From c0dbedac431a2038cd7382d4c0cd8ccb958675ac Mon Sep 17 00:00:00 2001 From: Marshall Dawson Date: Thu, 19 Oct 2017 09:45:16 -0600 Subject: x86/mtrr: Enable Rd/WrDram mod in AMD fixed MTRRs AMD's fixed MTRRs have RdDram and WrDram bits that route memory accesses to DRAM vs. MMIO. These are typically hidden for normal operation by clearing SYS_CFG[19] (MtrrFixDramModEn). According to BKDGs and AMD64 Programmer's Manual vol 2, this bit is clear at reset, should be set for configuration during POST, then cleared for normal operation. Attempting to modify the RdDram and WrDram settings without unhiding them causes a General Protection Fault. Add functions to enable and disable MtrrFixDramModEn. Unhide/hide as necessary when copying or writing the fixed MTRRs. Finally, modify sipi_vector.S to enable the bits prior to writing the fixed MTRRs and disable when complete. This functionality is compiled out on non-AMD platforms. BUG=b:68019051 TEST=Boot Kahlee, check steps with HDT Change-Id: Ie195131ff752400eb886dfccc39b314b4fa6b3f3 Signed-off-by: Marshall Dawson Reviewed-on: https://review.coreboot.org/23722 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin --- src/cpu/x86/mp_init.c | 4 ++++ src/cpu/x86/mtrr/mtrr.c | 30 +++++++++++++++++++++++++++++- src/cpu/x86/sipi_vector.S | 17 +++++++++++++++++ 3 files changed, 50 insertions(+), 1 deletion(-) (limited to 'src/cpu') diff --git a/src/cpu/x86/mp_init.c b/src/cpu/x86/mp_init.c index baa6aec998..92eb722eb4 100644 --- a/src/cpu/x86/mp_init.c +++ b/src/cpu/x86/mp_init.c @@ -299,6 +299,8 @@ static int save_bsp_msrs(char *start, int size) return -1; } + fixed_mtrrs_expose_amd_rwdram(); + msr_entry = (void *)start; for (i = 0; i < NUM_FIXED_MTRRS; i++) msr_entry = save_msr(fixed_mtrrs[i], msr_entry); @@ -310,6 +312,8 @@ static int save_bsp_msrs(char *start, int size) msr_entry = save_msr(MTRR_DEF_TYPE_MSR, msr_entry); + fixed_mtrrs_hide_amd_rwdram(); + return msr_count; } diff --git a/src/cpu/x86/mtrr/mtrr.c b/src/cpu/x86/mtrr/mtrr.c index c2c629cbe4..08312fbebf 100644 --- a/src/cpu/x86/mtrr/mtrr.c +++ b/src/cpu/x86/mtrr/mtrr.c @@ -36,8 +36,8 @@ #include #include #include -#if IS_ENABLED(CONFIG_X86_AMD_FIXED_MTRRS) #include +#if IS_ENABLED(CONFIG_X86_AMD_FIXED_MTRRS) #define MTRR_FIXED_WRBACK_BITS (MTRR_READ_MEM | MTRR_WRITE_MEM) #else #define MTRR_FIXED_WRBACK_BITS 0 @@ -83,6 +83,30 @@ void enable_fixed_mtrr(void) wrmsr(MTRR_DEF_TYPE_MSR, msr); } +void fixed_mtrrs_expose_amd_rwdram(void) +{ + msr_t syscfg; + + if (!IS_ENABLED(CONFIG_X86_AMD_FIXED_MTRRS)) + return; + + syscfg = rdmsr(SYSCFG_MSR); + syscfg.lo |= SYSCFG_MSR_MtrrFixDramModEn; + wrmsr(SYSCFG_MSR, syscfg); +} + +void fixed_mtrrs_hide_amd_rwdram(void) +{ + msr_t syscfg; + + if (!IS_ENABLED(CONFIG_X86_AMD_FIXED_MTRRS)) + return; + + syscfg = rdmsr(SYSCFG_MSR); + syscfg.lo &= ~SYSCFG_MSR_MtrrFixDramModEn; + wrmsr(SYSCFG_MSR, syscfg); +} + static void enable_var_mtrr(unsigned char deftype) { msr_t msr; @@ -310,6 +334,8 @@ static void commit_fixed_mtrrs(void) msr_t fixed_msrs[NUM_FIXED_MTRRS]; unsigned long msr_index[NUM_FIXED_MTRRS]; + fixed_mtrrs_expose_amd_rwdram(); + memset(&fixed_msrs, 0, sizeof(fixed_msrs)); msr_num = 0; @@ -351,6 +377,8 @@ static void commit_fixed_mtrrs(void) for (i = 0; i < ARRAY_SIZE(fixed_msrs); i++) wrmsr(msr_index[i], fixed_msrs[i]); enable_cache(); + fixed_mtrrs_hide_amd_rwdram(); + } void x86_setup_fixed_mtrrs_no_enable(void) diff --git a/src/cpu/x86/sipi_vector.S b/src/cpu/x86/sipi_vector.S index bd60c65a88..83606bd920 100644 --- a/src/cpu/x86/sipi_vector.S +++ b/src/cpu/x86/sipi_vector.S @@ -15,6 +15,7 @@ */ #include +#include /* The SIPI vector is responsible for initializing the APs in the sytem. It * loads microcode, sets up MSRs, and enables caching before calling into @@ -172,6 +173,15 @@ microcode_done: mov msr_count, %ebx test %ebx, %ebx jz 1f + +#if IS_ENABLED(CONFIG_X86_AMD_FIXED_MTRRS) + /* Allow modification of RdDram and WrDram bits */ + mov $SYSCFG_MSR, %ecx + rdmsr + or $SYSCFG_MSR_MtrrFixDramModEn, %eax + wrmsr +#endif + load_msr: mov (%edi), %ecx mov 4(%edi), %eax @@ -181,6 +191,13 @@ load_msr: dec %ebx jnz load_msr +#if IS_ENABLED(CONFIG_X86_AMD_FIXED_MTRRS) + mov $SYSCFG_MSR, %ecx + rdmsr + and $~SYSCFG_MSR_MtrrFixDramModEn, %eax + wrmsr +#endif + 1: /* Enable caching. */ mov %cr0, %eax -- cgit v1.2.3