/*
 * Copyright 2018 Advanced Micro Devices, Inc.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 */

#include <linux/io-64-nonatomic-lo-hi.h>

#include "amdgpu.h"
#include "amdgpu_gmc.h"
#include "amdgpu_ras.h"
#include "amdgpu_xgmi.h"

/**
 * amdgpu_gmc_pdb0_alloc - allocate vram for pdb0
 *
 * @adev: amdgpu_device pointer
 *
 * Allocate video memory for pdb0 and map it for CPU access
 * Returns 0 for success, error for failure.
 */
int amdgpu_gmc_pdb0_alloc(struct amdgpu_device *adev)
{
        int r;
        struct amdgpu_bo_param bp;
        u64 vram_size = adev->gmc.xgmi.node_segment_size * adev->gmc.xgmi.num_physical_nodes;
        uint32_t pde0_page_shift = adev->gmc.vmid0_page_table_block_size + 21;
        uint32_t npdes = (vram_size + (1ULL << pde0_page_shift) -1) >> pde0_page_shift;

        memset(&bp, 0, sizeof(bp));
        bp.size = PAGE_ALIGN((npdes + 1) * 8);
        bp.byte_align = PAGE_SIZE;
        bp.domain = AMDGPU_GEM_DOMAIN_VRAM;
        bp.flags = AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED |
                AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS;
        bp.type = ttm_bo_type_kernel;
        bp.resv = NULL;
        bp.bo_ptr_size = sizeof(struct amdgpu_bo);

        r = amdgpu_bo_create(adev, &bp, &adev->gmc.pdb0_bo);
        if (r)
                return r;

        r = amdgpu_bo_reserve(adev->gmc.pdb0_bo, false);
        if (unlikely(r != 0))
                goto bo_reserve_failure;

        r = amdgpu_bo_pin(adev->gmc.pdb0_bo, AMDGPU_GEM_DOMAIN_VRAM);
        if (r)
                goto bo_pin_failure;
        r = amdgpu_bo_kmap(adev->gmc.pdb0_bo, &adev->gmc.ptr_pdb0);
        if (r)
                goto bo_kmap_failure;

        amdgpu_bo_unreserve(adev->gmc.pdb0_bo);
        return 0;

bo_kmap_failure:
        amdgpu_bo_unpin(adev->gmc.pdb0_bo);
bo_pin_failure:
        amdgpu_bo_unreserve(adev->gmc.pdb0_bo);
bo_reserve_failure:
        amdgpu_bo_unref(&adev->gmc.pdb0_bo);
        return r;
}

/**
 * amdgpu_gmc_get_pde_for_bo - get the PDE for a BO
 *
 * @bo: the BO to get the PDE for
 * @level: the level in the PD hirarchy
 * @addr: resulting addr
 * @flags: resulting flags
 *
 * Get the address and flags to be used for a PDE (Page Directory Entry).
 */
void amdgpu_gmc_get_pde_for_bo(struct amdgpu_bo *bo, int level,
                               uint64_t *addr, uint64_t *flags)
{
        struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);

        switch (bo->tbo.mem.mem_type) {
        case TTM_PL_TT:
                *addr = bo->tbo.ttm->dma_address[0];
                break;
        case TTM_PL_VRAM:
                *addr = amdgpu_bo_gpu_offset(bo);
                break;
        default:
                *addr = 0;
                break;
        }
        *flags = amdgpu_ttm_tt_pde_flags(bo->tbo.ttm, &bo->tbo.mem);
        amdgpu_gmc_get_vm_pde(adev, level, addr, flags);
}

/*
 * amdgpu_gmc_pd_addr - return the address of the root directory
 */
uint64_t amdgpu_gmc_pd_addr(struct amdgpu_bo *bo)
{
        struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
        uint64_t pd_addr;

        /* TODO: move that into ASIC specific code */
        if (adev->asic_type >= CHIP_VEGA10) {
                uint64_t flags = AMDGPU_PTE_VALID;

                amdgpu_gmc_get_pde_for_bo(bo, -1, &pd_addr, &flags);
                pd_addr |= flags;
        } else {
                pd_addr = amdgpu_bo_gpu_offset(bo);
        }
        return pd_addr;
}

/**
 * amdgpu_gmc_set_pte_pde - update the page tables using CPU
 *
 * @adev: amdgpu_device pointer
 * @cpu_pt_addr: cpu address of the page table
 * @gpu_page_idx: entry in the page table to update
 * @addr: dst addr to write into pte/pde
 * @flags: access flags
 *
 * Update the page tables using CPU.
 */
int amdgpu_gmc_set_pte_pde(struct amdgpu_device *adev, void *cpu_pt_addr,
                                uint32_t gpu_page_idx, uint64_t addr,
                                uint64_t flags)
{
        void __iomem *ptr = (void *)cpu_pt_addr;
        uint64_t value;

        /*
         * The following is for PTE only. GART does not have PDEs.
        */
        value = addr & 0x0000FFFFFFFFF000ULL;
        value |= flags;
        writeq(value, ptr + (gpu_page_idx * 8));
        return 0;
}

/**
 * amdgpu_gmc_agp_addr - return the address in the AGP address space
 *
 * @bo: TTM BO which needs the address, must be in GTT domain
 *
 * Tries to figure out how to access the BO through the AGP aperture. Returns
 * AMDGPU_BO_INVALID_OFFSET if that is not possible.
 */
uint64_t amdgpu_gmc_agp_addr(struct ttm_buffer_object *bo)
{
        struct amdgpu_device *adev = amdgpu_ttm_adev(bo->bdev);

        if (bo->ttm->num_pages != 1 || bo->ttm->caching == ttm_cached)
                return AMDGPU_BO_INVALID_OFFSET;

        if (bo->ttm->dma_address[0] + PAGE_SIZE >= adev->gmc.agp_size)
                return AMDGPU_BO_INVALID_OFFSET;

        return adev->gmc.agp_start + bo->ttm->dma_address[0];
}

/**
 * amdgpu_gmc_vram_location - try to find VRAM location
 *
 * @adev: amdgpu device structure holding all necessary information
 * @mc: memory controller structure holding memory information
 * @base: base address at which to put VRAM
 *
 * Function will try to place VRAM at base address provided
 * as parameter.
 */
void amdgpu_gmc_vram_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc,
                              u64 base)
{
        uint64_t limit = (uint64_t)amdgpu_vram_limit << 20;

        mc->vram_start = base;
        mc->vram_end = mc->vram_start + mc->mc_vram_size - 1;
        if (limit && limit < mc->real_vram_size)
                mc->real_vram_size = limit;

        if (mc->xgmi.num_physical_nodes == 0) {
                mc->fb_start = mc->vram_start;
                mc->fb_end = mc->vram_end;
        }
        dev_info(adev->dev, "VRAM: %lluM 0x%016llX - 0x%016llX (%lluM used)\n",
                        mc->mc_vram_size >> 20, mc->vram_start,
                        mc->vram_end, mc->real_vram_size >> 20);
}

/** amdgpu_gmc_sysvm_location - place vram and gart in sysvm aperture
 *
 * @adev: amdgpu device structure holding all necessary information
 * @mc: memory controller structure holding memory information
 *
 * This function is only used if use GART for FB translation. In such
 * case, we use sysvm aperture (vmid0 page tables) for both vram
 * and gart (aka system memory) access.
 *
 * GPUVM (and our organization of vmid0 page tables) require sysvm
 * aperture to be placed at a location aligned with 8 times of native
 * page size. For example, if vm_context0_cntl.page_table_block_size
 * is 12, then native page size is 8G (2M*2^12), sysvm should start
 * with a 64G aligned address. For simplicity, we just put sysvm at
 * address 0. So vram start at address 0 and gart is right after vram.
 */
void amdgpu_gmc_sysvm_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc)
{
        u64 hive_vram_start = 0;
        u64 hive_vram_end = mc->xgmi.node_segment_size * mc->xgmi.num_physical_nodes - 1;
        mc->vram_start = mc->xgmi.node_segment_size * mc->xgmi.physical_node_id;
        mc->vram_end = mc->vram_start + mc->xgmi.node_segment_size - 1;
        mc->gart_start = hive_vram_end + 1;
        mc->gart_end = mc->gart_start + mc->gart_size - 1;
        mc->fb_start = hive_vram_start;
        mc->fb_end = hive_vram_end;
        dev_info(adev->dev, "VRAM: %lluM 0x%016llX - 0x%016llX (%lluM used)\n",
                        mc->mc_vram_size >> 20, mc->vram_start,
                        mc->vram_end, mc->real_vram_size >> 20);
        dev_info(adev->dev, "GART: %lluM 0x%016llX - 0x%016llX\n",
                        mc->gart_size >> 20, mc->gart_start, mc->gart_end);
}

/**
 * amdgpu_gmc_gart_location - try to find GART location
 *
 * @adev: amdgpu device structure holding all necessary information
 * @mc: memory controller structure holding memory information
 *
 * Function will place try to place GART before or after VRAM.
 * If GART size is bigger than space left then we ajust GART size.
 * Thus function will never fails.
 */
void amdgpu_gmc_gart_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc)
{
        const uint64_t four_gb = 0x100000000ULL;
        u64 size_af, size_bf;
        /*To avoid the hole, limit the max mc address to AMDGPU_GMC_HOLE_START*/
        u64 max_mc_address = min(adev->gmc.mc_mask, AMDGPU_GMC_HOLE_START - 1);

        /* VCE doesn't like it when BOs cross a 4GB segment, so align
         * the GART base on a 4GB boundary as well.
         */
        size_bf = mc->fb_start;
        size_af = max_mc_address + 1 - ALIGN(mc->fb_end + 1, four_gb);

        if (mc->gart_size > max(size_bf, size_af)) {
                dev_warn(adev->dev, "limiting GART\n");
                mc->gart_size = max(size_bf, size_af);
        }

        if ((size_bf >= mc->gart_size && size_bf < size_af) ||
            (size_af < mc->gart_size))
                mc->gart_start = 0;
        else
                mc->gart_start = max_mc_address - mc->gart_size + 1;

        mc->gart_start &= ~(four_gb - 1);
        mc->gart_end = mc->gart_start + mc->gart_size - 1;
        dev_info(adev->dev, "GART: %lluM 0x%016llX - 0x%016llX\n",
                        mc->gart_size >> 20, mc->gart_start, mc->gart_end);
}

/**
 * amdgpu_gmc_agp_location - try to find AGP location
 * @adev: amdgpu device structure holding all necessary information
 * @mc: memory controller structure holding memory information
 *
 * Function will place try to find a place for the AGP BAR in the MC address
 * space.
 *
 * AGP BAR will be assigned the largest available hole in the address space.
 * Should be called after VRAM and GART locations are setup.
 */
void amdgpu_gmc_agp_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc)
{
        const uint64_t sixteen_gb = 1ULL << 34;
        const uint64_t sixteen_gb_mask = ~(sixteen_gb - 1);
        u64 size_af, size_bf;

        if (amdgpu_sriov_vf(adev)) {
                mc->agp_start = 0xffffffffffff;
                mc->agp_end = 0x0;
                mc->agp_size = 0;

                return;
        }

        if (mc->fb_start > mc->gart_start) {
                size_bf = (mc->fb_start & sixteen_gb_mask) -
                        ALIGN(mc->gart_end + 1, sixteen_gb);
                size_af = mc->mc_mask + 1 - ALIGN(mc->fb_end + 1, sixteen_gb);
        } else {
                size_bf = mc->fb_start & sixteen_gb_mask;
                size_af = (mc->gart_start & sixteen_gb_mask) -
                        ALIGN(mc->fb_end + 1, sixteen_gb);
        }

        if (size_bf > size_af) {
                mc->agp_start = (mc->fb_start - size_bf) & sixteen_gb_mask;
                mc->agp_size = size_bf;
        } else {
                mc->agp_start = ALIGN(mc->fb_end + 1, sixteen_gb);
                mc->agp_size = size_af;
        }

        mc->agp_end = mc->agp_start + mc->agp_size - 1;
        dev_info(adev->dev, "AGP: %lluM 0x%016llX - 0x%016llX\n",
                        mc->agp_size >> 20, mc->agp_start, mc->agp_end);
}

/**
 * amdgpu_gmc_filter_faults - filter VM faults
 *
 * @adev: amdgpu device structure
 * @addr: address of the VM fault
 * @pasid: PASID of the process causing the fault
 * @timestamp: timestamp of the fault
 *
 * Returns:
 * True if the fault was filtered and should not be processed further.
 * False if the fault is a new one and needs to be handled.
 */
bool amdgpu_gmc_filter_faults(struct amdgpu_device *adev, uint64_t addr,
                              uint16_t pasid, uint64_t timestamp)
{
        struct amdgpu_gmc *gmc = &adev->gmc;

        uint64_t stamp, key = addr << 4 | pasid;
        struct amdgpu_gmc_fault *fault;
        uint32_t hash;

        /* If we don't have space left in the ring buffer return immediately */
        stamp = max(timestamp, AMDGPU_GMC_FAULT_TIMEOUT + 1) -
                AMDGPU_GMC_FAULT_TIMEOUT;
        if (gmc->fault_ring[gmc->last_fault].timestamp >= stamp)
                return true;

        /* Try to find the fault in the hash */
        hash = hash_64(key, AMDGPU_GMC_FAULT_HASH_ORDER);
        fault = &gmc->fault_ring[gmc->fault_hash[hash].idx];
        while (fault->timestamp >= stamp) {
                uint64_t tmp;

                if (fault->key == key)
                        return true;

                tmp = fault->timestamp;
                fault = &gmc->fault_ring[fault->next];

                /* Check if the entry was reused */
                if (fault->timestamp >= tmp)
                        break;
        }

        /* Add the fault to the ring */
        fault = &gmc->fault_ring[gmc->last_fault];
        fault->key = key;
        fault->timestamp = timestamp;

        /* And update the hash */
        fault->next = gmc->fault_hash[hash].idx;
        gmc->fault_hash[hash].idx = gmc->last_fault++;
        return false;
}

int amdgpu_gmc_ras_late_init(struct amdgpu_device *adev)
{
        int r;

        if (adev->umc.ras_funcs &&
            adev->umc.ras_funcs->ras_late_init) {
                r = adev->umc.ras_funcs->ras_late_init(adev);
                if (r)
                        return r;
        }

        if (adev->mmhub.ras_funcs &&
            adev->mmhub.ras_funcs->ras_late_init) {
                r = adev->mmhub.ras_funcs->ras_late_init(adev);
                if (r)
                        return r;
        }

        if (!adev->gmc.xgmi.connected_to_cpu)
                adev->gmc.xgmi.ras_funcs = &xgmi_ras_funcs;

        if (adev->gmc.xgmi.ras_funcs &&
            adev->gmc.xgmi.ras_funcs->ras_late_init) {
                r = adev->gmc.xgmi.ras_funcs->ras_late_init(adev);
                if (r)
                        return r;
        }

        return 0;
}

void amdgpu_gmc_ras_fini(struct amdgpu_device *adev)
{
        if (adev->umc.ras_funcs &&
            adev->umc.ras_funcs->ras_fini)
                adev->umc.ras_funcs->ras_fini(adev);

        if (adev->mmhub.ras_funcs &&
            adev->mmhub.ras_funcs->ras_fini)
                amdgpu_mmhub_ras_fini(adev);

        if (adev->gmc.xgmi.ras_funcs &&
            adev->gmc.xgmi.ras_funcs->ras_fini)
                adev->gmc.xgmi.ras_funcs->ras_fini(adev);
}

        /*
         * The latest engine allocation on gfx9/10 is:
         * Engine 2, 3: firmware
         * Engine 0, 1, 4~16: amdgpu ring,
         *                    subject to change when ring number changes
         * Engine 17: Gart flushes
         */
#define GFXHUB_FREE_VM_INV_ENGS_BITMAP          0x1FFF3
#define MMHUB_FREE_VM_INV_ENGS_BITMAP           0x1FFF3

int amdgpu_gmc_allocate_vm_inv_eng(struct amdgpu_device *adev)
{
        struct amdgpu_ring *ring;
        unsigned vm_inv_engs[AMDGPU_MAX_VMHUBS] =
                {GFXHUB_FREE_VM_INV_ENGS_BITMAP, MMHUB_FREE_VM_INV_ENGS_BITMAP,
                GFXHUB_FREE_VM_INV_ENGS_BITMAP};
        unsigned i;
        unsigned vmhub, inv_eng;

        for (i = 0; i < adev->num_rings; ++i) {
                ring = adev->rings[i];
                vmhub = ring->funcs->vmhub;

                if (ring == &adev->mes.ring)
                        continue;

                inv_eng = ffs(vm_inv_engs[vmhub]);
                if (!inv_eng) {
                        dev_err(adev->dev, "no VM inv eng for ring %s\n",
                                ring->name);
                        return -EINVAL;
                }

                ring->vm_inv_eng = inv_eng - 1;
                vm_inv_engs[vmhub] &= ~(1 << ring->vm_inv_eng);

                dev_info(adev->dev, "ring %s uses VM inv eng %u on hub %u\n",
                         ring->name, ring->vm_inv_eng, ring->funcs->vmhub);
        }

        return 0;
}

/**
 * amdgpu_tmz_set -- check and set if a device supports TMZ
 * @adev: amdgpu_device pointer
 *
 * Check and set if an the device @adev supports Trusted Memory
 * Zones (TMZ).
 */
void amdgpu_gmc_tmz_set(struct amdgpu_device *adev)
{
        switch (adev->asic_type) {
        case CHIP_RAVEN:
        case CHIP_RENOIR:
                if (amdgpu_tmz == 0) {
                        adev->gmc.tmz_enabled = false;
                        dev_info(adev->dev,
                                 "Trusted Memory Zone (TMZ) feature disabled (cmd line)\n");
                } else {
                        adev->gmc.tmz_enabled = true;
                        dev_info(adev->dev,
                                 "Trusted Memory Zone (TMZ) feature enabled\n");
                }
                break;
        case CHIP_NAVI10:
        case CHIP_NAVI14:
        case CHIP_NAVI12:
        case CHIP_VANGOGH:
                /* Don't enable it by default yet.
                 */
                if (amdgpu_tmz < 1) {
                        adev->gmc.tmz_enabled = false;
                        dev_info(adev->dev,
                                 "Trusted Memory Zone (TMZ) feature disabled as experimental (default)\n");
                } else {
                        adev->gmc.tmz_enabled = true;
                        dev_info(adev->dev,
                                 "Trusted Memory Zone (TMZ) feature enabled as experimental (cmd line)\n");
                }
                break;
        default:
                adev->gmc.tmz_enabled = false;
                dev_warn(adev->dev,
                         "Trusted Memory Zone (TMZ) feature not supported\n");
                break;
        }
}

/**
 * amdgpu_noretry_set -- set per asic noretry defaults
 * @adev: amdgpu_device pointer
 *
 * Set a per asic default for the no-retry parameter.
 *
 */
void amdgpu_gmc_noretry_set(struct amdgpu_device *adev)
{
        struct amdgpu_gmc *gmc = &adev->gmc;

        switch (adev->asic_type) {
        case CHIP_VEGA10:
        case CHIP_VEGA20:
        case CHIP_ARCTURUS:
        case CHIP_ALDEBARAN:
                /*
                 * noretry = 0 will cause kfd page fault tests fail
                 * for some ASICs, so set default to 1 for these ASICs.
                 */
                if (amdgpu_noretry == -1)
                        gmc->noretry = 1;
                else
                        gmc->noretry = amdgpu_noretry;
                break;
        case CHIP_RAVEN:
        default:
                /* Raven currently has issues with noretry
                 * regardless of what we decide for other
                 * asics, we should leave raven with
                 * noretry = 0 until we root cause the
                 * issues.
                 *
                 * default this to 0 for now, but we may want
                 * to change this in the future for certain
                 * GPUs as it can increase performance in
                 * certain cases.
                 */
                if (amdgpu_noretry == -1)
                        gmc->noretry = 0;
                else
                        gmc->noretry = amdgpu_noretry;
                break;
        }
}

void amdgpu_gmc_set_vm_fault_masks(struct amdgpu_device *adev, int hub_type,
                                   bool enable)
{
        struct amdgpu_vmhub *hub;
        u32 tmp, reg, i;

        hub = &adev->vmhub[hub_type];
        for (i = 0; i < 16; i++) {
                reg = hub->vm_context0_cntl + hub->ctx_distance * i;

                tmp = RREG32(reg);
                if (enable)
                        tmp |= hub->vm_cntx_cntl_vm_fault;
                else
                        tmp &= ~hub->vm_cntx_cntl_vm_fault;

                WREG32(reg, tmp);
        }
}

void amdgpu_gmc_get_vbios_allocations(struct amdgpu_device *adev)
{
        unsigned size;

        /*
         * TODO:
         * Currently there is a bug where some memory client outside
         * of the driver writes to first 8M of VRAM on S3 resume,
         * this overrides GART which by default gets placed in first 8M and
         * causes VM_FAULTS once GTT is accessed.
         * Keep the stolen memory reservation until the while this is not solved.
         */
        switch (adev->asic_type) {
        case CHIP_VEGA10:
        case CHIP_RAVEN:
        case CHIP_RENOIR:
                adev->mman.keep_stolen_vga_memory = true;
                break;
        default:
                adev->mman.keep_stolen_vga_memory = false;
                break;
        }

        if (amdgpu_sriov_vf(adev) ||
            !amdgpu_device_ip_get_ip_block(adev, AMD_IP_BLOCK_TYPE_DCE)) {
                size = 0;
        } else {
                size = amdgpu_gmc_get_vbios_fb_size(adev);

                if (adev->mman.keep_stolen_vga_memory)
                        size = max(size, (unsigned)AMDGPU_VBIOS_VGA_ALLOCATION);
        }

        /* set to 0 if the pre-OS buffer uses up most of vram */
        if ((adev->gmc.real_vram_size - size) < (8 * 1024 * 1024))
                size = 0;

        if (size > AMDGPU_VBIOS_VGA_ALLOCATION) {
                adev->mman.stolen_vga_size = AMDGPU_VBIOS_VGA_ALLOCATION;
                adev->mman.stolen_extended_size = size - adev->mman.stolen_vga_size;
        } else {
                adev->mman.stolen_vga_size = size;
                adev->mman.stolen_extended_size = 0;
        }
}

/**
 * amdgpu_gmc_init_pdb0 - initialize PDB0
 *
 * @adev: amdgpu_device pointer
 *
 * This function is only used when GART page table is used
 * for FB address translatioin. In such a case, we construct
 * a 2-level system VM page table: PDB0->PTB, to cover both
 * VRAM of the hive and system memory.
 *
 * PDB0 is static, initialized once on driver initialization.
 * The first n entries of PDB0 are used as PTE by setting
 * P bit to 1, pointing to VRAM. The n+1'th entry points
 * to a big PTB covering system memory.
 *
 */
void amdgpu_gmc_init_pdb0(struct amdgpu_device *adev)
{
        int i;
        uint64_t flags = adev->gart.gart_pte_flags; //TODO it is UC. explore NC/RW?
        /* Each PDE0 (used as PTE) covers (2^vmid0_page_table_block_size)*2M
         */
        u64 vram_size = adev->gmc.xgmi.node_segment_size * adev->gmc.xgmi.num_physical_nodes;
        u64 pde0_page_size = (1ULL<<adev->gmc.vmid0_page_table_block_size)<<21;
        u64 vram_addr = adev->vm_manager.vram_base_offset -
                adev->gmc.xgmi.physical_node_id * adev->gmc.xgmi.node_segment_size;
        u64 vram_end = vram_addr + vram_size;
        u64 gart_ptb_gpu_pa = amdgpu_gmc_vram_pa(adev, adev->gart.bo);

        flags |= AMDGPU_PTE_VALID | AMDGPU_PTE_READABLE;
        flags |= AMDGPU_PTE_WRITEABLE;
        flags |= AMDGPU_PTE_SNOOPED;
        flags |= AMDGPU_PTE_FRAG((adev->gmc.vmid0_page_table_block_size + 9*1));
        flags |= AMDGPU_PDE_PTE;

        /* The first n PDE0 entries are used as PTE,
         * pointing to vram
         */
        for (i = 0; vram_addr < vram_end; i++, vram_addr += pde0_page_size)
                amdgpu_gmc_set_pte_pde(adev, adev->gmc.ptr_pdb0, i, vram_addr, flags);

        /* The n+1'th PDE0 entry points to a huge
         * PTB who has more than 512 entries each
         * pointing to a 4K system page
         */
        flags = AMDGPU_PTE_VALID;
        flags |= AMDGPU_PDE_BFS(0) | AMDGPU_PTE_SNOOPED;
        /* Requires gart_ptb_gpu_pa to be 4K aligned */
        amdgpu_gmc_set_pte_pde(adev, adev->gmc.ptr_pdb0, i, gart_ptb_gpu_pa, flags);
}

/**
 * amdgpu_gmc_vram_mc2pa - calculate vram buffer's physical address from MC
 * address
 *
 * @adev: amdgpu_device pointer
 * @mc_addr: MC address of buffer
 */
uint64_t amdgpu_gmc_vram_mc2pa(struct amdgpu_device *adev, uint64_t mc_addr)
{
        return mc_addr - adev->gmc.vram_start + adev->vm_manager.vram_base_offset;
}

/**
 * amdgpu_gmc_vram_pa - calculate vram buffer object's physical address from
 * GPU's view
 *
 * @adev: amdgpu_device pointer
 * @bo: amdgpu buffer object
 */
uint64_t amdgpu_gmc_vram_pa(struct amdgpu_device *adev, struct amdgpu_bo *bo)
{
        return amdgpu_gmc_vram_mc2pa(adev, amdgpu_bo_gpu_offset(bo));
}

/**
 * amdgpu_gmc_vram_cpu_pa - calculate vram buffer object's physical address
 * from CPU's view
 *
 * @adev: amdgpu_device pointer
 * @bo: amdgpu buffer object
 */
uint64_t amdgpu_gmc_vram_cpu_pa(struct amdgpu_device *adev, struct amdgpu_bo *bo)
{
        return amdgpu_bo_gpu_offset(bo) - adev->gmc.vram_start + adev->gmc.aper_base;
}