From: Brijesh Singh Date: Wed, 15 Aug 2018 16:11:25 -0500 Subject: [PATCH] crypto: ccp - add timeout support in the SEV command Origin: https://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6.git/commit/?h=linus&id=3702a0585e64d70d5bf73bf3e943b8d6005b72c1 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 051b8c6bae64..19dde2e866c9 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 @@ static irqreturn_t psp_irq_handler(int irq, void *data) 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_CMDRESP); + + 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); @@ -154,8 +177,18 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret) iowrite32(reg, psp->io_regs + PSP_CMDRESP); /* 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; @@ -886,6 +919,9 @@ void psp_pci_init(void) psp_master = sp->psp_data; + psp_timeout = psp_probe_timeout; + + if (sev_get_api_version()) goto err; -- 2.18.0