smm_init.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <cpu/x86/msr.h>
#include <cpu/x86/mtrr.h>
#include <cpu/amd/mtrr.h>
#include <cpu/amd/msr.h>
#include <cpu/x86/cache.h>
#include <cpu/x86/smm.h>
#include <cpu/x86/smi_deprecated.h>
#include <string.h>
 
void smm_init(void)
{
        msr_t msr, syscfg_orig, mtrr_aseg_orig;
 
        /* Back up MSRs for later restore */
        syscfg_orig = rdmsr(SYSCFG_MSR);
        mtrr_aseg_orig = rdmsr(MTRR_FIX_16K_A0000);
 
        /* MTRR changes don't like an enabled cache */
        disable_cache();
 
        msr = syscfg_orig;
 
        /* Allow changes to MTRR extended attributes */
        msr.lo |= SYSCFG_MSR_MtrrFixDramModEn;
        /* turn the extended attributes off until we fix
         * them so A0000 is routed to memory
         */
        msr.lo &= ~SYSCFG_MSR_MtrrFixDramEn;
        wrmsr(SYSCFG_MSR, msr);
 
        /* set DRAM access to 0xa0000 */
        msr.lo = 0x18181818;
        msr.hi = 0x18181818;
        wrmsr(MTRR_FIX_16K_A0000, msr);
 
        /* enable the extended features */
        msr = syscfg_orig;
        msr.lo |= SYSCFG_MSR_MtrrFixDramModEn;
        msr.lo |= SYSCFG_MSR_MtrrFixDramEn;
        wrmsr(SYSCFG_MSR, msr);
 
        enable_cache();
        /* copy the real SMM handler */
        memcpy((void *)SMM_BASE, _binary_smm_start,
                _binary_smm_end - _binary_smm_start);
        wbinvd();
        disable_cache();
 
        /* Restore SYSCFG and MTRR */
        wrmsr(SYSCFG_MSR, syscfg_orig);
        wrmsr(MTRR_FIX_16K_A0000, mtrr_aseg_orig);
        enable_cache();
 
        /* CPU MSR are set in CPU init */
}
 
void smm_init_completion(void)
{
}