The behavior of the SEV-legacy commands is altered when the SNP firmware is in the INIT state. When SNP is in INIT state, all the SEV-legacy commands that cause the firmware to write to memory must be in the firmware state before issuing the command.. A command buffer may contains a system physical address that the firmware may write to. There are two cases that need to be handled: 1) system physical address points to a guest memory 2) system physical address points to a host memory To handle the case #1, map_firmware_writeable() helper simply changes the page state in the RMP table before and after the command is sent to the firmware. For the case #2, the map_firmware_writeable() replaces the host system physical memory with a pre-allocated firmware page, and after the command completes, the unmap_firmware_writeable() copies the content from pre-allocated firmware page to original host system physical. The unmap_firmware_writeable() calls a __sev_do_cmd_locked() to clear the immutable bit from the memory page. To support the nested calling, a separate command buffer is required. Allocate a backup command buffer and keep reference count of it. If a nested call is detected then use the backup cmd_buf to complete the command submission. Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx> --- drivers/crypto/ccp/sev-dev.c | 348 ++++++++++++++++++++++++++++++++++- drivers/crypto/ccp/sev-dev.h | 12 ++ 2 files changed, 350 insertions(+), 10 deletions(-) diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index cbf77cbf1887..c886d76ae31d 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -265,12 +265,299 @@ void snp_free_firmware_page(void *addr) } EXPORT_SYMBOL(snp_free_firmware_page); +static int alloc_snp_host_map(struct sev_device *sev) +{ + struct page *page; + int i; + + for (i = 0; i < MAX_SNP_HOST_MAP_BUFS; i++) { + struct snp_host_map *map = &sev->snp_host_map[i]; + + memset(map, 0, sizeof(*map)); + + page = __snp_alloc_firmware_pages(GFP_KERNEL_ACCOUNT, + get_order(SEV_FW_BLOB_MAX_SIZE)); + if (!page) + return -ENOMEM; + + map->host = page_address(page); + } + + return 0; +} + +static void free_snp_host_map(struct sev_device *sev) +{ + int i; + + for (i = 0; i < MAX_SNP_HOST_MAP_BUFS; i++) { + struct snp_host_map *map = &sev->snp_host_map[i]; + + if (map->host) { + __snp_free_firmware_pages(virt_to_page(map->host), + get_order(SEV_FW_BLOB_MAX_SIZE)); + memset(map, 0, sizeof(*map)); + } + } +} + +static int map_firmware_writeable(u64 *paddr, u32 len, bool guest, struct snp_host_map *map) +{ + unsigned int npages = PAGE_ALIGN(len) >> PAGE_SHIFT; + int ret; + + map->active = false; + + if (!paddr || !len) + return 0; + + map->paddr = *paddr; + map->len = len; + + /* If paddr points to a guest memory then change the page state to firmwware. */ + if (guest) { + struct rmpupdate val = {}; + + val.immutable = true; + val.assigned = true; + ret = snp_set_rmptable_state(*paddr, npages, &val, true, false); + if (ret) + return ret; + + goto done; + } + + if (unlikely(!map->host)) + return -EINVAL; + + /* Check if the pre-allocated buffer can be used to fullfil the request. */ + if (unlikely(len > SEV_FW_BLOB_MAX_SIZE)) + return -EINVAL; + + /* Set the paddr to use an intermediate firmware buffer */ + *paddr = __psp_pa(map->host); + +done: + map->active = true; + return 0; +} + +static int unmap_firmware_writeable(u64 *paddr, u32 len, bool guest, struct snp_host_map *map) +{ + unsigned int npages = PAGE_ALIGN(len) >> PAGE_SHIFT; + int ret; + + if (!map->active) + return 0; + + /* If paddr points to a guest memory then restore the page state to hypervisor. */ + if (guest) { + struct rmpupdate val = {}; + + ret = snp_set_rmptable_state(*paddr, npages, &val, true, true); + if (ret) + return ret; + + goto done; + } + + /* Copy the response data firmware buffer to the callers buffer. */ + memcpy(__va(__sme_clr(map->paddr)), map->host, min_t(size_t, len, map->len)); + *paddr = map->paddr; + +done: + map->active = false; + return 0; +} + +static bool sev_legacy_cmd_buf_writable(int cmd) +{ + switch (cmd) { + case SEV_CMD_PLATFORM_STATUS: + case SEV_CMD_GUEST_STATUS: + case SEV_CMD_LAUNCH_START: + case SEV_CMD_RECEIVE_START: + case SEV_CMD_LAUNCH_MEASURE: + case SEV_CMD_SEND_START: + case SEV_CMD_SEND_UPDATE_DATA: + case SEV_CMD_SEND_UPDATE_VMSA: + case SEV_CMD_PEK_CSR: + case SEV_CMD_PDH_CERT_EXPORT: + case SEV_CMD_GET_ID: + case SEV_CMD_ATTESTATION_REPORT: + return true; + default: + return false; + } +} + +#define prep_buffer(name, addr, len, guest, map) \ + func(&((typeof(name *))cmd_buf)->addr, ((typeof(name *))cmd_buf)->len, guest, map) + +static int __snp_cmd_buf_copy(int cmd, void *cmd_buf, bool to_fw, int fw_err) +{ + int (*func)(u64 *paddr, u32 len, bool guest, struct snp_host_map *map); + struct sev_device *sev = psp_master->sev_data; + struct rmpupdate val = {}; + bool from_fw = !to_fw; + int ret; + + /* + * After the command is completed, change the command buffer memory to + * hypervisor state. + * + * The immutable bit is automatically cleared by the firmware, so + * no not need to reclaim the page. + */ + if (from_fw && sev_legacy_cmd_buf_writable(cmd)) { + ret = snp_set_rmptable_state(__pa(cmd_buf), 1, &val, true, false); + if (ret) + return ret; + + /* No need to go further if firmware failed to execute command. */ + if (fw_err) + return 0; + } + + if (to_fw) + func = map_firmware_writeable; + else + func = unmap_firmware_writeable; + + /* + * A command buffer may contains a system physical address. If the address + * points to a host memory then use an intermediate firmware page otherwise + * change the page state in the RMP table. + */ + switch (cmd) { + case SEV_CMD_PDH_CERT_EXPORT: + if (prep_buffer(struct sev_data_pdh_cert_export, pdh_cert_address, + pdh_cert_len, false, &sev->snp_host_map[0])) + goto err; + if (prep_buffer(struct sev_data_pdh_cert_export, cert_chain_address, + cert_chain_len, false, &sev->snp_host_map[1])) + goto err; + break; + case SEV_CMD_GET_ID: + if (prep_buffer(struct sev_data_get_id, address, len, + false, &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_PEK_CSR: + if (prep_buffer(struct sev_data_pek_csr, address, len, + false, &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_LAUNCH_UPDATE_DATA: + if (prep_buffer(struct sev_data_launch_update_data, address, len, + true, &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_LAUNCH_UPDATE_VMSA: + if (prep_buffer(struct sev_data_launch_update_vmsa, address, len, + true, &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_LAUNCH_MEASURE: + if (prep_buffer(struct sev_data_launch_measure, address, len, + false, &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_LAUNCH_UPDATE_SECRET: + if (prep_buffer(struct sev_data_launch_secret, guest_address, guest_len, + true, &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_DBG_DECRYPT: + if (prep_buffer(struct sev_data_dbg, dst_addr, len, false, + &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_DBG_ENCRYPT: + if (prep_buffer(struct sev_data_dbg, dst_addr, len, true, + &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_ATTESTATION_REPORT: + if (prep_buffer(struct sev_data_attestation_report, address, len, + false, &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_SEND_START: + if (prep_buffer(struct sev_data_send_start, session_address, + session_len, false, &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_SEND_UPDATE_DATA: + if (prep_buffer(struct sev_data_send_update_data, hdr_address, hdr_len, + false, &sev->snp_host_map[0])) + goto err; + if (prep_buffer(struct sev_data_send_update_data, trans_address, + trans_len, false, &sev->snp_host_map[1])) + goto err; + break; + case SEV_CMD_SEND_UPDATE_VMSA: + if (prep_buffer(struct sev_data_send_update_vmsa, hdr_address, hdr_len, + false, &sev->snp_host_map[0])) + goto err; + if (prep_buffer(struct sev_data_send_update_vmsa, trans_address, + trans_len, false, &sev->snp_host_map[1])) + goto err; + break; + case SEV_CMD_RECEIVE_UPDATE_DATA: + if (prep_buffer(struct sev_data_receive_update_data, guest_address, + guest_len, true, &sev->snp_host_map[0])) + goto err; + break; + case SEV_CMD_RECEIVE_UPDATE_VMSA: + if (prep_buffer(struct sev_data_receive_update_vmsa, guest_address, + guest_len, true, &sev->snp_host_map[0])) + goto err; + break; + default: + break; + } + + /* The command buffer need to be in the firmware state. */ + if (to_fw && sev_legacy_cmd_buf_writable(cmd)) { + val.assigned = true; + val.immutable = true; + ret = snp_set_rmptable_state(__pa(cmd_buf), 1, &val, true, false); + if (ret) + return ret; + } + + return 0; + +err: + return -EINVAL; +} + +static inline bool need_firmware_copy(int cmd) +{ + struct sev_device *sev = psp_master->sev_data; + + /* After SNP is INIT'ed, the behavior of legacy SEV command is changed. */ + return ((cmd < SEV_CMD_SNP_INIT) && sev->snp_inited) ? true : false; +} + +static int snp_aware_copy_to_firmware(int cmd, void *data) +{ + return __snp_cmd_buf_copy(cmd, data, true, 0); +} + +static int snp_aware_copy_from_firmware(int cmd, void *data, int fw_err) +{ + return __snp_cmd_buf_copy(cmd, data, false, fw_err); +} + static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret) { struct psp_device *psp = psp_master; struct sev_device *sev; unsigned int phys_lsb, phys_msb; unsigned int reg, ret = 0; + void *cmd_buf; int buf_len; if (!psp || !psp->sev_data) @@ -290,12 +577,26 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret) * work for some memory, e.g. vmalloc'd addresses, and @data may not be * physically contiguous. */ - if (data) - memcpy(sev->cmd_buf, data, buf_len); + if (data) { + if (unlikely(sev->cmd_buf_active > 2)) + return -EBUSY; + + cmd_buf = sev->cmd_buf_active ? sev->cmd_buf_backup : sev->cmd_buf; + + memcpy(cmd_buf, data, buf_len); + sev->cmd_buf_active++; + + /* + * The behavior of the SEV-legacy commands is altered when the + * SNP firmware is in the INIT state. + */ + if (need_firmware_copy(cmd) && snp_aware_copy_to_firmware(cmd, sev->cmd_buf)) + return -EFAULT; + } /* Get the physical address of the command buffer */ - phys_lsb = data ? lower_32_bits(__psp_pa(sev->cmd_buf)) : 0; - phys_msb = data ? upper_32_bits(__psp_pa(sev->cmd_buf)) : 0; + phys_lsb = data ? lower_32_bits(__psp_pa(cmd_buf)) : 0; + phys_msb = data ? upper_32_bits(__psp_pa(cmd_buf)) : 0; dev_dbg(sev->dev, "sev command id %#x buffer 0x%08x%08x timeout %us\n", cmd, phys_msb, phys_lsb, psp_timeout); @@ -336,15 +637,24 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret) ret = -EIO; } - print_hex_dump_debug("(out): ", DUMP_PREFIX_OFFSET, 16, 2, data, - buf_len, false); - /* * Copy potential output from the PSP back to data. Do this even on * failure in case the caller wants to glean something from the error. */ - if (data) - memcpy(data, sev->cmd_buf, buf_len); + if (data) { + /* + * Restore the page state after the command completes. + */ + if (need_firmware_copy(cmd) && + snp_aware_copy_from_firmware(cmd, cmd_buf, ret)) + return -EFAULT; + + memcpy(data, cmd_buf, buf_len); + sev->cmd_buf_active--; + } + + print_hex_dump_debug("(out): ", DUMP_PREFIX_OFFSET, 16, 2, data, + buf_len, false); return ret; } @@ -1216,10 +1526,12 @@ int sev_dev_init(struct psp_device *psp) if (!sev) goto e_err; - sev->cmd_buf = (void *)devm_get_free_pages(dev, GFP_KERNEL, 0); + sev->cmd_buf = (void *)devm_get_free_pages(dev, GFP_KERNEL, 1); if (!sev->cmd_buf) goto e_sev; + sev->cmd_buf_backup = (uint8_t *)sev->cmd_buf + PAGE_SIZE; + psp->sev_data = sev; sev->dev = dev; @@ -1271,6 +1583,12 @@ static void sev_firmware_shutdown(struct sev_device *sev) sev_es_tmr = NULL; } + /* + * The host map need to clear the immutable bit so it must be free'd before the + * SNP firmware shutdown. + */ + free_snp_host_map(sev); + sev_snp_shutdown(NULL); } @@ -1330,6 +1648,14 @@ void sev_pci_init(void) */ dev_err(sev->dev, "SEV-SNP: failed to INIT error %#x\n", error); } + + /* + * Allocate the intermediate buffers used for the legacy command handling. + */ + if (alloc_snp_host_map(sev)) { + dev_notice(sev->dev, "Failed to alloc host map (disabling legacy SEV)\n"); + goto skip_legacy; + } } /* Obtain the TMR memory area for SEV-ES use */ @@ -1359,12 +1685,14 @@ void sev_pci_init(void) if (rc) dev_err(sev->dev, "SEV: failed to INIT error %#x\n", error); +skip_legacy: dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_inited ? "-SNP" : "", sev->api_major, sev->api_minor, sev->build); return; err: + free_snp_host_map(sev); psp_master->sev_data = NULL; } diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h index 186ad20cbd24..fe5d7a3ebace 100644 --- a/drivers/crypto/ccp/sev-dev.h +++ b/drivers/crypto/ccp/sev-dev.h @@ -29,11 +29,20 @@ #define SEV_CMDRESP_CMD_SHIFT 16 #define SEV_CMDRESP_IOC BIT(0) +#define MAX_SNP_HOST_MAP_BUFS 2 + struct sev_misc_dev { struct kref refcount; struct miscdevice misc; }; +struct snp_host_map { + u64 paddr; + u32 len; + void *host; + bool active; +}; + struct sev_device { struct device *dev; struct psp_device *psp; @@ -52,8 +61,11 @@ struct sev_device { u8 build; void *cmd_buf; + void *cmd_buf_backup; + int cmd_buf_active; bool snp_inited; + struct snp_host_map snp_host_map[MAX_SNP_HOST_MAP_BUFS]; }; int sev_dev_init(struct psp_device *psp); -- 2.17.1