// SPDX-License-Identifier: GPL-2.0-only
/*
 * Memory Encryption Support Common Code
 *
 * Copyright (C) 2016 Advanced Micro Devices, Inc.
 *
 * Author: Tom Lendacky <thomas.lendacky@amd.com>
 */

#include <linux/dma-direct.h>
#include <linux/dma-mapping.h>
#include <linux/swiotlb.h>
#include <linux/cc_platform.h>
#include <linux/mem_encrypt.h>
#include <linux/virtio_anchor.h>

#include <asm/sev.h>

/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
bool force_dma_unencrypted(struct device *dev)
{
        /*
         * For SEV, all DMA must be to unencrypted addresses.
         */
        if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
                return true;

        /*
         * For SME, all DMA must be to unencrypted addresses if the
         * device does not support DMA to addresses that include the
         * encryption mask.
         */
        if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {
                u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask));
                u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask,
                                                dev->bus_dma_limit);

                if (dma_dev_mask <= dma_enc_mask)
                        return true;
        }

        return false;
}

static void print_mem_encrypt_feature_info(void)
{
        pr_info("Memory Encryption Features active: ");

        switch (cc_vendor) {
        case CC_VENDOR_INTEL:
                pr_cont("Intel TDX\n");
                break;
        case CC_VENDOR_AMD:
                pr_cont("AMD");

                /* Secure Memory Encryption */
                if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {
                /*
                 * SME is mutually exclusive with any of the SEV
                 * features below.
                */
                        pr_cont(" SME\n");
                        return;
                }

                /* Secure Encrypted Virtualization */
                if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
                        pr_cont(" SEV");

                /* Encrypted Register State */
                if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
                        pr_cont(" SEV-ES");

                /* Secure Nested Paging */
                if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
                        pr_cont(" SEV-SNP");

                pr_cont("\n");

                sev_show_status();

                break;
        default:
                pr_cont("Unknown\n");
        }
}

/* Architecture __weak replacement functions */
void __init mem_encrypt_init(void)
{
        if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT))
                return;

        /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
        swiotlb_update_mem_attributes();

        snp_secure_tsc_prepare();

        print_mem_encrypt_feature_info();
}

void __init mem_encrypt_setup_arch(void)
{
        phys_addr_t total_mem = memblock_phys_mem_size();
        unsigned long size;

        /*
         * Do RMP table fixups after the e820 tables have been setup by
         * e820__memory_setup().
         */
        if (cc_platform_has(CC_ATTR_HOST_SEV_SNP))
                snp_fixup_e820_tables();

        if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
                return;

        /*
         * For SEV and TDX, all DMA has to occur via shared/unencrypted pages.
         * Kernel uses SWIOTLB to make this happen without changing device
         * drivers. However, depending on the workload being run, the
         * default 64MB of SWIOTLB may not be enough and SWIOTLB may
         * run out of buffers for DMA, resulting in I/O errors and/or
         * performance degradation especially with high I/O workloads.
         *
         * Adjust the default size of SWIOTLB using a percentage of guest
         * memory for SWIOTLB buffers. Also, as the SWIOTLB bounce buffer
         * memory is allocated from low memory, ensure that the adjusted size
         * is within the limits of low available memory.
         *
         * The percentage of guest memory used here for SWIOTLB buffers
         * is more of an approximation of the static adjustment which
         * 64MB for <1G, and ~128M to 256M for 1G-to-4G, i.e., the 6%
         */
        size = total_mem * 6 / 100;
        size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G);
        swiotlb_adjust_size(size);

        /* Set restricted memory access for virtio. */
        virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
}