diff options
| -rw-r--r-- | arch/x86/include/asm/pat.h | 2 | ||||
| -rw-r--r-- | arch/x86/mm/init.c | 6 | ||||
| -rw-r--r-- | arch/x86/mm/pat.c | 81 | ||||
| -rw-r--r-- | arch/x86/xen/enlighten.c | 5 |
4 files changed, 60 insertions, 34 deletions
diff --git a/arch/x86/include/asm/pat.h b/arch/x86/include/asm/pat.h index cdcff7f7f694..ca6c228d5e62 100644 --- a/arch/x86/include/asm/pat.h +++ b/arch/x86/include/asm/pat.h @@ -6,7 +6,7 @@ bool pat_enabled(void); extern void pat_init(void); -void pat_init_cache_modes(void); +void pat_init_cache_modes(u64); extern int reserve_memtype(u64 start, u64 end, enum page_cache_mode req_pcm, enum page_cache_mode *ret_pcm); diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 1d553186c434..8533b46e6bee 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -40,7 +40,7 @@ */ uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM] = { [_PAGE_CACHE_MODE_WB ] = 0 | 0 , - [_PAGE_CACHE_MODE_WC ] = _PAGE_PWT | 0 , + [_PAGE_CACHE_MODE_WC ] = 0 | _PAGE_PCD, [_PAGE_CACHE_MODE_UC_MINUS] = 0 | _PAGE_PCD, [_PAGE_CACHE_MODE_UC ] = _PAGE_PWT | _PAGE_PCD, [_PAGE_CACHE_MODE_WT ] = 0 | _PAGE_PCD, @@ -50,11 +50,11 @@ EXPORT_SYMBOL(__cachemode2pte_tbl); uint8_t __pte2cachemode_tbl[8] = { [__pte2cm_idx( 0 | 0 | 0 )] = _PAGE_CACHE_MODE_WB, - [__pte2cm_idx(_PAGE_PWT | 0 | 0 )] = _PAGE_CACHE_MODE_WC, + [__pte2cm_idx(_PAGE_PWT | 0 | 0 )] = _PAGE_CACHE_MODE_UC_MINUS, [__pte2cm_idx( 0 | _PAGE_PCD | 0 )] = _PAGE_CACHE_MODE_UC_MINUS, [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | 0 )] = _PAGE_CACHE_MODE_UC, [__pte2cm_idx( 0 | 0 | _PAGE_PAT)] = _PAGE_CACHE_MODE_WB, - [__pte2cm_idx(_PAGE_PWT | 0 | _PAGE_PAT)] = _PAGE_CACHE_MODE_WC, + [__pte2cm_idx(_PAGE_PWT | 0 | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC_MINUS, [__pte2cm_idx(0 | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC_MINUS, [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC, }; diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 476d0780560f..6dc7826e4797 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -68,8 +68,6 @@ static int __init pat_debug_setup(char *str) } __setup("debugpat", pat_debug_setup); -static u64 __read_mostly boot_pat_state; - #ifdef CONFIG_X86_PAT /* * X86 PAT uses page flags WC and Uncached together to keep track of @@ -177,14 +175,12 @@ static enum page_cache_mode pat_get_cache_mode(unsigned pat_val, char *msg) * configuration. * Using lower indices is preferred, so we start with highest index. */ -void pat_init_cache_modes(void) +void pat_init_cache_modes(u64 pat) { - int i; enum page_cache_mode cache; char pat_msg[33]; - u64 pat; + int i; - rdmsrl(MSR_IA32_CR_PAT, pat); pat_msg[32] = 0; for (i = 7; i >= 0; i--) { cache = pat_get_cache_mode((pat >> (i * 8)) & 7, @@ -198,24 +194,33 @@ void pat_init_cache_modes(void) static void pat_bsp_init(u64 pat) { + u64 tmp_pat; + if (!cpu_has_pat) { pat_disable("PAT not supported by CPU."); return; } - rdmsrl(MSR_IA32_CR_PAT, boot_pat_state); - if (!boot_pat_state) { + if (!pat_enabled()) + goto done; + + rdmsrl(MSR_IA32_CR_PAT, tmp_pat); + if (!tmp_pat) { pat_disable("PAT MSR is 0, disabled."); return; } wrmsrl(MSR_IA32_CR_PAT, pat); - pat_init_cache_modes(); +done: + pat_init_cache_modes(pat); } static void pat_ap_init(u64 pat) { + if (!pat_enabled()) + return; + if (!cpu_has_pat) { /* * If this happens we are on a secondary CPU, but switched to @@ -231,25 +236,45 @@ void pat_init(void) { u64 pat; - if (!pat_enabled()) - return; - - /* - * Set PWT to Write-Combining. All other bits stay the same: - * - * PTE encoding used in Linux: - * PAT - * |PCD - * ||PWT - * ||| - * 000 WB _PAGE_CACHE_WB - * 001 WC _PAGE_CACHE_WC - * 010 UC- _PAGE_CACHE_UC_MINUS - * 011 UC _PAGE_CACHE_UC - * PAT bit unused - */ - pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) | - PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC); + if (!pat_enabled()) { + /* + * No PAT. Emulate the PAT table that corresponds to the two + * cache bits, PWT (Write Through) and PCD (Cache Disable). This + * setup is the same as the BIOS default setup when the system + * has PAT but the "nopat" boot option has been specified. This + * emulated PAT table is used when MSR_IA32_CR_PAT returns 0. + * + * PTE encoding used: + * + * PCD + * |PWT PAT + * || slot + * 00 0 WB : _PAGE_CACHE_MODE_WB + * 01 1 WT : _PAGE_CACHE_MODE_WT + * 10 2 UC-: _PAGE_CACHE_MODE_UC_MINUS + * 11 3 UC : _PAGE_CACHE_MODE_UC + * + * NOTE: When WC or WP is used, it is redirected to UC- per + * the default setup in __cachemode2pte_tbl[]. + */ + pat = PAT(0, WB) | PAT(1, WT) | PAT(2, UC_MINUS) | PAT(3, UC) | + PAT(4, WB) | PAT(5, WT) | PAT(6, UC_MINUS) | PAT(7, UC); + } else { + /* + * PTE encoding used in Linux: + * PAT + * |PCD + * ||PWT + * ||| + * 000 WB _PAGE_CACHE_WB + * 001 WC _PAGE_CACHE_WC + * 010 UC- _PAGE_CACHE_UC_MINUS + * 011 UC _PAGE_CACHE_UC + * PAT bit unused + */ + pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) | + PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC); + } if (!boot_cpu_done) { pat_bsp_init(pat); diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 46957ead3060..53233a9beea9 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1467,6 +1467,7 @@ asmlinkage __visible void __init xen_start_kernel(void) { struct physdev_set_iopl set_iopl; unsigned long initrd_start = 0; + u64 pat; int rc; if (!xen_start_info) @@ -1574,8 +1575,8 @@ asmlinkage __visible void __init xen_start_kernel(void) * Modify the cache mode translation tables to match Xen's PAT * configuration. */ - - pat_init_cache_modes(); + rdmsrl(MSR_IA32_CR_PAT, pat); + pat_init_cache_modes(pat); /* keep using Xen gdt for now; no urgent need to change it */ |