From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E17462E610F; Wed, 11 Jun 2025 16:45:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749660345; cv=none; b=JtqoujcH5+cmfbcJuj9TBoM3iKOjeXYPLArwVT4Kp5qvHvLd8eKu43k+nH0eQrStPtB1TbMkQuIkyWuogiJ7OCzXu+SbEVt6XTCDXv3CeNjhgEQaeiuKLJDTWG9v5I3k2jC2HG/dMFaF1uIjnN8YzQZmAwRCc7t3y1zWM9akN5w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749660345; c=relaxed/simple; bh=6YiYld9w2Hx+Iaj5LQHXe+nPaanJ0QWZp6uRgHqygvg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lqbPo8pK9woMxkbpi0auu+ivMHxP5rcbsS9a46Q7SPl7IRFS0Qry278MoRpkhZ8Z7Ifj8Ek7SysV6iIgiQMI7vu/6wXOtuIvgkR1Ak8LGkcRcJ33XSqh2luwsNXFTpp5maNaLUuXIOCdo4mF3ybVuuLCRlLN2C6oVaRqoxDpj/E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uMVTcWwy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="uMVTcWwy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CEC1BC4CEE3; Wed, 11 Jun 2025 16:45:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749660344; bh=6YiYld9w2Hx+Iaj5LQHXe+nPaanJ0QWZp6uRgHqygvg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uMVTcWwy/s+ucZwaGP8pT9hxCeH3a3YxGDrchK3bts5ut5zRaDXovnEb0zDVpFYKJ YsTzZkpM0FK4qVF17OSvkGoXCqtdhzL0UNv0fGyqjtnwJP9Z+oLR54ZxtTvIc8BXSh XhEclKcOLqwZ//oqKFdVlwv5o6zfKyDU38LvX6LQ9q9MTecVWLx5iTv5YWKpbhXnVu PxWJCt3li6cKlcMv6clfO+y76bHU8jckGWcdM8psSNFRL713EH8q4PBHoZU3ZlTo9x TJSgxbup7/bumeblBTC8UZyySOEJ0H1SY3mohqGSRBTtd9cEodSUoGrbOy+syWBjHu Wl5gjiZ2AiAdA== Date: Wed, 11 Jun 2025 19:45:39 +0300 From: Jarkko Sakkinen To: Prachotan Bathi Cc: Peter Huewe , Jason Gunthorpe , Stuart Yoder , linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/1] tpm_crb_ffa: handle tpm busy return code Message-ID: References: <20250610213505.3881352-1-prachotan.bathi@arm.com> <20250610213505.3881352-2-prachotan.bathi@arm.com> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250610213505.3881352-2-prachotan.bathi@arm.com> On Tue, Jun 10, 2025 at 04:35:05PM -0500, Prachotan Bathi wrote: > Platforms supporting direct message request v2 can > support SPs that support multiple services. > If the TPM service is sharing the SP with another service, > it could get an error code of BUSY if the other service is > in process. > This adds a parameterized variable (default 2000ms) > that indicates the maximum time to keep retrying for. > When the TPM service returns a BUSY error code, we sleep > 50-100us before retrying again, until we are over the > busy timeout. > > Signed-off-by: Prachotan Bathi > --- > drivers/char/tpm/tpm_crb_ffa.c | 78 +++++++++++++++++++++++----------- > 1 file changed, 54 insertions(+), 24 deletions(-) > > diff --git a/drivers/char/tpm/tpm_crb_ffa.c b/drivers/char/tpm/tpm_crb_ffa.c > index 4ead61f01299..122984e15971 100644 > --- a/drivers/char/tpm/tpm_crb_ffa.c > +++ b/drivers/char/tpm/tpm_crb_ffa.c > @@ -10,6 +10,8 @@ > #define pr_fmt(fmt) "CRB_FFA: " fmt > > #include > +#include > +#include > #include "tpm_crb_ffa.h" > > /* TPM service function status codes */ > @@ -178,6 +180,17 @@ int tpm_crb_ffa_init(void) > } > EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); > > +static unsigned int busy_timeout = 2000; > +/** > + * busy_timeout - Maximum time to retry before giving up on busy > + * > + * This parameter defines the maximum time in milliseconds to retry > + * sending a message to the TPM service before giving up. > + */ > +module_param(busy_timeout, uint, 0644); > +MODULE_PARM_DESC(busy_timeout, > + "Maximum time to retry before giving up on busy"); > + > static int __tpm_crb_ffa_send_recieve(unsigned long func_id, > unsigned long a0, > unsigned long a1, > @@ -191,34 +204,51 @@ static int __tpm_crb_ffa_send_recieve(unsigned long func_id, > > msg_ops = tpm_crb_ffa->ffa_dev->ops->msg_ops; > > - if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { > - memset(&tpm_crb_ffa->direct_msg_data2, 0x00, > - sizeof(struct ffa_send_direct_data2)); > + ktime_t start; > + ktime_t stop; > + > + start = ktime_get(); > + stop = ktime_add(start, ms_to_ktime(busy_timeout)); > + > + do { > + if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { > + memset(&tpm_crb_ffa->direct_msg_data2, 0x00, > + sizeof(struct ffa_send_direct_data2)); > > - tpm_crb_ffa->direct_msg_data2.data[0] = func_id; > - tpm_crb_ffa->direct_msg_data2.data[1] = a0; > - tpm_crb_ffa->direct_msg_data2.data[2] = a1; > - tpm_crb_ffa->direct_msg_data2.data[3] = a2; > + tpm_crb_ffa->direct_msg_data2.data[0] = func_id; > + tpm_crb_ffa->direct_msg_data2.data[1] = a0; > + tpm_crb_ffa->direct_msg_data2.data[2] = a1; > + tpm_crb_ffa->direct_msg_data2.data[3] = a2; > > - ret = msg_ops->sync_send_receive2(tpm_crb_ffa->ffa_dev, > + ret = msg_ops->sync_send_receive2(tpm_crb_ffa->ffa_dev, > &tpm_crb_ffa->direct_msg_data2); > - if (!ret) > - ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[0]); > - } else { > - memset(&tpm_crb_ffa->direct_msg_data, 0x00, > - sizeof(struct ffa_send_direct_data)); > - > - tpm_crb_ffa->direct_msg_data.data1 = func_id; > - tpm_crb_ffa->direct_msg_data.data2 = a0; > - tpm_crb_ffa->direct_msg_data.data3 = a1; > - tpm_crb_ffa->direct_msg_data.data4 = a2; > - > - ret = msg_ops->sync_send_receive(tpm_crb_ffa->ffa_dev, > - &tpm_crb_ffa->direct_msg_data); > - if (!ret) > - ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data.data1); > - } > + if (!ret) > + ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[0]); > + } else { > + memset(&tpm_crb_ffa->direct_msg_data, 0x00, > + sizeof(struct ffa_send_direct_data)); > > + tpm_crb_ffa->direct_msg_data.data1 = func_id; > + tpm_crb_ffa->direct_msg_data.data2 = a0; > + tpm_crb_ffa->direct_msg_data.data3 = a1; > + tpm_crb_ffa->direct_msg_data.data4 = a2; > + > + ret = msg_ops->sync_send_receive(tpm_crb_ffa->ffa_dev, > + &tpm_crb_ffa->direct_msg_data); > + if (!ret) > + ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data.data1); > + } > + // Check if the TPM service returned busy > + if (ret == -EBUSY) > + pr_err("TPM says busy, trying again, value, ret: %d\n", > + ret); > + else > + // If TPM did not return busy, we are done, exit the loop > + break; > + // Sleep for a short time before retrying to avoid busy looping > + usleep_range(50, 100); > + } while (ktime_before(ktime_get(), stop)); > + // If we are here, we either got a valid response or we are over the busy timeout Please use "/* */". We don't use C++ comment style: https://www.kernel.org/doc/html/v6.14/process/coding-style.html#commenting BR, Jarkko