From 8347b99473a313be6549a5b940bc3c56a71be81c Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 6 Apr 2021 15:49:48 -0700 Subject: crypto: ccp: Play nice with vmalloc'd memory for SEV command structs Copy the incoming @data comman to an internal buffer so that callers can put SEV command buffers on the stack without running afoul of CONFIG_VMAP_STACK=y, i.e. without bombing on vmalloc'd pointers. As of today, the largest supported command takes a 68 byte buffer, i.e. pretty much every command can be put on the stack. Because sev_cmd_mutex is held for the entirety of a transaction, only a single bounce buffer is required. Use the internal buffer unconditionally, as the majority of in-kernel users will soon switch to using the stack. At that point, checking virt_addr_valid() becomes (negligible) overhead in most cases, and supporting both paths slightly increases complexity. Since the commands are all quite small, the cost of the copies is insignificant compared to the latency of communicating with the PSP. Allocate a full page for the buffer as opportunistic preparation for SEV-SNP, which requires the command buffer to be in firmware state for commands that trigger memory writes from the PSP firmware. Using a full page now will allow SEV-SNP support to simply transition the page as needed. Cc: Brijesh Singh Cc: Borislav Petkov Cc: Tom Lendacky Cc: Christophe Leroy Signed-off-by: Sean Christopherson Message-Id: <20210406224952.4177376-5-seanjc@google.com> Reviewed-by: Brijesh Singh Acked-by: Tom Lendacky Signed-off-by: Paolo Bonzini --- drivers/crypto/ccp/sev-dev.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/crypto/ccp/sev-dev.h') diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h index dd5c4fe82914..e1572f408577 100644 --- a/drivers/crypto/ccp/sev-dev.h +++ b/drivers/crypto/ccp/sev-dev.h @@ -52,6 +52,8 @@ struct sev_device { u8 api_major; u8 api_minor; u8 build; + + void *cmd_buf; }; int sev_dev_init(struct psp_device *psp); -- cgit v1.2.3 From 38103671aad38e888743dd26c767869cfc15adca Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 6 Apr 2021 15:49:50 -0700 Subject: crypto: ccp: Use the stack and common buffer for status commands Drop the dedicated status_cmd_buf and instead use a local variable for PLATFORM_STATUS. Now that the low level helper uses an internal buffer for all commands, using the stack for the upper layers is safe even when running with CONFIG_VMAP_STACK=y. Signed-off-by: Sean Christopherson Message-Id: <20210406224952.4177376-7-seanjc@google.com> Reviewed-by: Brijesh Singh Acked-by: Tom Lendacky Signed-off-by: Paolo Bonzini --- drivers/crypto/ccp/sev-dev.c | 27 ++++++++++++--------------- drivers/crypto/ccp/sev-dev.h | 1 - 2 files changed, 12 insertions(+), 16 deletions(-) (limited to 'drivers/crypto/ccp/sev-dev.h') diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 246b281b6376..2184c4a67d35 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -316,15 +316,14 @@ static int sev_platform_shutdown(int *error) static int sev_get_platform_state(int *state, int *error) { - struct sev_device *sev = psp_master->sev_data; + struct sev_user_data_status data; int rc; - rc = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS, - &sev->status_cmd_buf, error); + rc = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS, &data, error); if (rc) return rc; - *state = sev->status_cmd_buf.state; + *state = data.state; return rc; } @@ -362,15 +361,14 @@ static int sev_ioctl_do_reset(struct sev_issue_cmd *argp, bool writable) static int sev_ioctl_do_platform_status(struct sev_issue_cmd *argp) { - struct sev_device *sev = psp_master->sev_data; - struct sev_user_data_status *data = &sev->status_cmd_buf; + struct sev_user_data_status data; int ret; - ret = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS, data, &argp->error); + ret = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS, &data, &argp->error); if (ret) return ret; - if (copy_to_user((void __user *)argp->data, data, sizeof(*data))) + if (copy_to_user((void __user *)argp->data, &data, sizeof(data))) ret = -EFAULT; return ret; @@ -469,21 +467,20 @@ EXPORT_SYMBOL_GPL(psp_copy_user_blob); static int sev_get_api_version(void) { struct sev_device *sev = psp_master->sev_data; - struct sev_user_data_status *status; + struct sev_user_data_status status; int error = 0, ret; - status = &sev->status_cmd_buf; - ret = sev_platform_status(status, &error); + ret = sev_platform_status(&status, &error); if (ret) { dev_err(sev->dev, "SEV: failed to get status. Error: %#x\n", error); return 1; } - sev->api_major = status->api_major; - sev->api_minor = status->api_minor; - sev->build = status->build; - sev->state = status->state; + sev->api_major = status.api_major; + sev->api_minor = status.api_minor; + sev->build = status.build; + sev->state = status.state; return 0; } diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h index e1572f408577..0fd21433f627 100644 --- a/drivers/crypto/ccp/sev-dev.h +++ b/drivers/crypto/ccp/sev-dev.h @@ -46,7 +46,6 @@ struct sev_device { unsigned int int_rcvd; wait_queue_head_t int_queue; struct sev_misc_dev *misc; - struct sev_user_data_status status_cmd_buf; struct sev_data_init init_cmd_buf; u8 api_major; -- cgit v1.2.3 From a402e35177797d736dd3dc2d8537c1c9ac90d54a Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 6 Apr 2021 15:49:51 -0700 Subject: crypto: ccp: Use the stack and common buffer for INIT command Drop the dedicated init_cmd_buf and instead use a local variable. Now that the low level helper uses an internal buffer for all commands, using the stack for the upper layers is safe even when running with CONFIG_VMAP_STACK=y. Signed-off-by: Sean Christopherson Message-Id: <20210406224952.4177376-8-seanjc@google.com> Reviewed-by: Brijesh Singh Acked-by: Tom Lendacky Signed-off-by: Paolo Bonzini --- drivers/crypto/ccp/sev-dev.c | 10 ++++++---- drivers/crypto/ccp/sev-dev.h | 1 - 2 files changed, 6 insertions(+), 5 deletions(-) (limited to 'drivers/crypto/ccp/sev-dev.h') diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 2184c4a67d35..6ee703176049 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -234,6 +234,7 @@ static int sev_do_cmd(int cmd, void *data, int *psp_ret) static int __sev_platform_init_locked(int *error) { struct psp_device *psp = psp_master; + struct sev_data_init data; struct sev_device *sev; int rc = 0; @@ -245,6 +246,7 @@ static int __sev_platform_init_locked(int *error) if (sev->state == SEV_STATE_INIT) return 0; + memset(&data, 0, sizeof(data)); if (sev_es_tmr) { u64 tmr_pa; @@ -254,12 +256,12 @@ static int __sev_platform_init_locked(int *error) */ tmr_pa = __pa(sev_es_tmr); - sev->init_cmd_buf.flags |= SEV_INIT_FLAGS_SEV_ES; - sev->init_cmd_buf.tmr_address = tmr_pa; - sev->init_cmd_buf.tmr_len = SEV_ES_TMR_SIZE; + data.flags |= SEV_INIT_FLAGS_SEV_ES; + data.tmr_address = tmr_pa; + data.tmr_len = SEV_ES_TMR_SIZE; } - rc = __sev_do_cmd_locked(SEV_CMD_INIT, &sev->init_cmd_buf, error); + rc = __sev_do_cmd_locked(SEV_CMD_INIT, &data, error); if (rc) return rc; diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h index 0fd21433f627..666c21eb81ab 100644 --- a/drivers/crypto/ccp/sev-dev.h +++ b/drivers/crypto/ccp/sev-dev.h @@ -46,7 +46,6 @@ struct sev_device { unsigned int int_rcvd; wait_queue_head_t int_queue; struct sev_misc_dev *misc; - struct sev_data_init init_cmd_buf; u8 api_major; u8 api_minor; -- cgit v1.2.3