From: Wei Huang Date: Wed, 6 Apr 2011 08:02:13 +0000 (+0100) Subject: x86, amd, MTRR: remove k8_enable_fixed_iorrs() X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=ca7690b505ce7a6c0ebf9d91854fd94ace29219f;p=xen.git x86, amd, MTRR: remove k8_enable_fixed_iorrs() AMD64 defines two special bits (bit 3 and 4) RdMem and WrMem in fixed MTRR type. Their values are supposed to be 0 after BIOS hands the control to OS according to AMD BKDG. Unless OS specificially turn them on, they are kept 0 all the time. As a result, k8_enable_fixed_iorrs() is unnecessary and removed from upstream kernel (see https://patchwork.kernel.org/patch/11425/). This patch does the same thing. Signed-off-by: Wei Huang --- diff --git a/xen/arch/x86/cpu/mtrr/generic.c b/xen/arch/x86/cpu/mtrr/generic.c index cd3c740da6..0f6c6b1b0c 100644 --- a/xen/arch/x86/cpu/mtrr/generic.c +++ b/xen/arch/x86/cpu/mtrr/generic.c @@ -115,20 +115,6 @@ void mtrr_wrmsr(unsigned int msr, uint64_t msr_content) mtrr_state.overlapped = is_var_mtrr_overlapped(&mtrr_state); } -/** - * Enable and allow read/write of extended fixed-range MTRR bits on K8 CPUs - * see AMD publication no. 24593, chapter 3.2.1 for more information - */ -static inline void k8_enable_fixed_iorrs(void) -{ - uint64_t msr_content; - - rdmsrl(MSR_K8_SYSCFG, msr_content); - mtrr_wrmsr(MSR_K8_SYSCFG, msr_content - | K8_MTRRFIXRANGE_DRAM_ENABLE - | K8_MTRRFIXRANGE_DRAM_MODIFY); -} - /** * Checks and updates an fixed-range MTRR if it differs from the value it * should have. If K8 extenstions are wanted, update the K8 SYSCFG MSR also. @@ -145,10 +131,6 @@ static void set_fixed_range(int msr, int * changed, unsigned int * msrwords) val = ((uint64_t)msrwords[1] << 32) | msrwords[0]; if (msr_content != val) { - if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD && - boot_cpu_data.x86 == 15 && - ((msrwords[0] | msrwords[1]) & K8_MTRR_RDMEM_WRMEM_MASK)) - k8_enable_fixed_iorrs(); mtrr_wrmsr(msr, val); *changed = TRUE; }