On Fri, Mar 07, 2025 at 10:58:13AM +0000, Jonathan McDowell wrote: > From: Jonathan McDowell <noodles@xxxxxxxx> > > Lazy flushing of TPM auth sessions was introduced to speed up IMA > measurments into the TPM. Make use of it in tpm2_get_random as well, > which has the added benefit of not needlessly cleaning up the session > that IMA is using when there are no userspace accesses taking place. > > Command trace before for every call: > > hwrng (0x00000161): 14 (52965242 ns) > hwrng (0x00000176): 48 (161612432 ns) > hwrng (0x00000165): 10 (2410494 ns) > hwrng (0x0000017B): 117 (70699883 ns) > hwrng (0x0000017B): 117 (70959666 ns) > hwrng (0x00000165): 10 (2756827 ns) > > After, with repeated calls showing no setup: > > hwrng (0x00000161): 14 (53044582 ns) > hwrng (0x00000176): 48 (160491333 ns) > hwrng (0x00000165): 10 (2408220 ns) > hwrng (0x0000017B): 117 (70695037 ns) > hwrng (0x0000017B): 117 (70994984 ns) > hwrng (0x0000017B): 117 (70195388 ns) > hwrng (0x0000017B): 117 (70973835 ns) > > Signed-off-by: Jonathan McDowell <noodles@xxxxxxxx> > --- > drivers/char/tpm/tpm2-cmd.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c > index dfdcbd009720..524d802ede26 100644 > --- a/drivers/char/tpm/tpm2-cmd.c > +++ b/drivers/char/tpm/tpm2-cmd.c > @@ -359,7 +359,6 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) > } while (retries-- && total < max); > > tpm_buf_destroy(&buf); > - tpm2_end_auth_session(chip); > > return total ? total : -EIO; > out: > -- > 2.48.1 > Thanks for this. It is a good catch! I'll apply this over the weekend when I apply Arm FF-A driver patches. Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> BR, Jarkko
