crypto: ccp - do not request interrupt on cmd completion when irqs disabled

While sending a command to the PSP, we always requested an interrupt
from the PSP after command completion.  This worked for most cases.  For
the special case of irqs being disabled -- e.g. when running within
crashdump or kexec contexts, we should not set the SEV_CMDRESP_IOC flag,
so the PSP knows to not attempt interrupt delivery.

Fixes: 8ef979584ea8 ("crypto: ccp: Add panic notifier for SEV/SNP firmware shutdown on kdump")
Based-on-patch-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Amit Shah <amit.shah@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index ff17b651c32834bb6f8de321300ec1ed16bbef76..af018afd9cd7fc68c5f9004e2d0a2ee162d8c4b9 100644 (file)
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -910,7 +910,18 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
 
        sev->int_rcvd = 0;
 
-       reg = FIELD_PREP(SEV_CMDRESP_CMD, cmd) | SEV_CMDRESP_IOC;
+       reg = FIELD_PREP(SEV_CMDRESP_CMD, cmd);
+
+       /*
+        * If invoked during panic handling, local interrupts are disabled so
+        * the PSP command completion interrupt can't be used.
+        * sev_wait_cmd_ioc() already checks for interrupts disabled and
+        * polls for PSP command completion.  Ensure we do not request an
+        * interrupt from the PSP if irqs disabled.
+        */
+       if (!irqs_disabled())
+               reg |= SEV_CMDRESP_IOC;
+
        iowrite32(reg, sev->io_regs + sev->vdata->cmdresp_reg);
 
        /* wait for command completion */