From 3702a0585e64d70d5bf73bf3e943b8d6005b72c1 Mon Sep 17 00:00:00 2001 From: Brijesh Singh Date: Wed, 15 Aug 2018 16:11:25 -0500 Subject: [PATCH] crypto: ccp - add timeout support in the SEV command Currently, the CCP driver assumes that the SEV command issued to the PSP will always return (i.e. it will never hang). But recently, firmware bugs have shown that a command can hang. Since of the SEV commands are used in probe routines, this can cause boot hangs and/or loss of virtualization capabilities. To protect against firmware bugs, add a timeout in the SEV command execution flow. If a command does not complete within the specified timeout then return -ETIMEOUT and stop the driver from executing any further commands since the state of the SEV firmware is unknown. Cc: Tom Lendacky Cc: Gary Hook Cc: Herbert Xu Cc: linux-kernel@vger.kernel.org Signed-off-by: Brijesh Singh Signed-off-by: Herbert Xu --- drivers/crypto/ccp/psp-dev.c | 46 +++++++++++++++++++++++++++++++++++++++----- 1 file changed, 41 insertions(+), 5 deletions(-) diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c index 218739b..72790d8 100644 --- a/drivers/crypto/ccp/psp-dev.c +++ b/drivers/crypto/ccp/psp-dev.c @@ -38,6 +38,17 @@ static DEFINE_MUTEX(sev_cmd_mutex); static struct sev_misc_dev *misc_dev; static struct psp_device *psp_master; +static int psp_cmd_timeout = 100; +module_param(psp_cmd_timeout, int, 0644); +MODULE_PARM_DESC(psp_cmd_timeout, " default timeout value, in seconds, for PSP commands"); + +static int psp_probe_timeout = 5; +module_param(psp_probe_timeout, int, 0644); +MODULE_PARM_DESC(psp_probe_timeout, " default timeout value, in seconds, during PSP device probe"); + +static bool psp_dead; +static int psp_timeout; + static struct psp_device *psp_alloc_struct(struct sp_device *sp) { struct device *dev = sp->dev; @@ -82,10 +93,19 @@ done: return IRQ_HANDLED; } -static void sev_wait_cmd_ioc(struct psp_device *psp, unsigned int *reg) +static int sev_wait_cmd_ioc(struct psp_device *psp, + unsigned int *reg, unsigned int timeout) { - wait_event(psp->sev_int_queue, psp->sev_int_rcvd); + int ret; + + ret = wait_event_timeout(psp->sev_int_queue, + psp->sev_int_rcvd, timeout * HZ); + if (!ret) + return -ETIMEDOUT; + *reg = ioread32(psp->io_regs + psp->vdata->cmdresp_reg); + + return 0; } static int sev_cmd_buffer_len(int cmd) @@ -133,12 +153,15 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret) if (!psp) return -ENODEV; + if (psp_dead) + return -EBUSY; + /* Get the physical address of the command buffer */ phys_lsb = data ? lower_32_bits(__psp_pa(data)) : 0; phys_msb = data ? upper_32_bits(__psp_pa(data)) : 0; - dev_dbg(psp->dev, "sev command id %#x buffer 0x%08x%08x\n", - cmd, phys_msb, phys_lsb); + dev_dbg(psp->dev, "sev command id %#x buffer 0x%08x%08x timeout %us\n", + cmd, phys_msb, phys_lsb, psp_timeout); print_hex_dump_debug("(in): ", DUMP_PREFIX_OFFSET, 16, 2, data, sev_cmd_buffer_len(cmd), false); @@ -154,7 +177,18 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret) iowrite32(reg, psp->io_regs + psp->vdata->cmdresp_reg); /* wait for command completion */ - sev_wait_cmd_ioc(psp, ®); + ret = sev_wait_cmd_ioc(psp, ®, psp_timeout); + if (ret) { + if (psp_ret) + *psp_ret = 0; + + dev_err(psp->dev, "sev command %#x timed out, disabling PSP \n", cmd); + psp_dead = true; + + return ret; + } + + psp_timeout = psp_cmd_timeout; if (psp_ret) *psp_ret = reg & PSP_CMDRESP_ERR_MASK; @@ -888,6 +922,8 @@ void psp_pci_init(void) psp_master = sp->psp_data; + psp_timeout = psp_probe_timeout; + if (sev_get_api_version()) goto err; -- 2.7.4