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crypto: ccp - add timeout support in the SEV command

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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 <thomas.lendacky@amd.com>
Cc: Gary Hook <Gary.Hook@amd.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Brijesh Singh 2018-08-15 16:11:25 -05:00 committed by Herbert Xu
parent f3569fd613
commit e82867fddd
1 changed files with 41 additions and 5 deletions
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46
drivers/crypto/ccp/psp-dev.c
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@ -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->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, &reg);
ret = sev_wait_cmd_ioc(psp, &reg, 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;