linux-kernel - Re: [PATCH] crypto: ccp: Add a quirk to firmware update

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Message-ID: <YvKua80NyjOcGgTD@kernel.org>
Date:   Tue, 9 Aug 2022 21:58:51 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Jarkko Sakkinen <jarkko@...fian.com>,
        Harald Hoyer <harald@...fian.com>,
        Brijesh Singh <brijesh.singh@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        "open list:AMD CRYPTOGRAPHIC COPROCESSOR (CCP) DRIVER - SE..." 
        <linux-crypto@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] crypto: ccp: Add a quirk to firmware update

On Tue, Aug 09, 2022 at 10:57:16AM -0500, Tom Lendacky wrote:
> On 8/7/22 19:15, Jarkko Sakkinen wrote:
> > From: Jarkko Sakkinen <jarkko@...fian.com>
> 
> Looks good, just some minor commit message and comment changes requested.
> 
> > 
> > A quirk for fixing the committed TCB version, when upgrading from earlier
> > firmware version than 1.33.01. This is a known issue, and the documented
> 
> ", when upgrading from earlier firmware version than 1.33.01" => "when
> upgrading from a firmware version earlier than 1.50"
> 
> > workaround is to load the firmware twice.
> > 
> > The issue realizes in a machine where the upgrade is done from firmware
> > reporting having SEV API version 1.49, and requires the following
> > workaround:
> 
> Replace the above paragraph with just: "Currently, this issue requires the
> following workaround:"
> 
> > 
> > sudo modprobe -r kvm_amd
> > sudo modprobe -r ccp
> > sudo modprobe ccp
> > sudo modprobe kvm_amd
> > 
> > Implement this workaround inside kernel by checking whether the API
> > version is less than 1.50, and if so, download the firmware twice.
> > This addresses the TCB version issue.
> > 
> > Link: https://lore.kernel.org/all/de02389f-249d-f565-1136-4af3655fab2a@profian.com/
> > Reported-by: Harald Hoyer <harald@...fian.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko@...fian.com>
> > ---
> >   drivers/crypto/ccp/sev-dev.c | 16 ++++++++++++++--
> >   1 file changed, 14 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> > index 799b476fc3e8..8ae26c5c64f6 100644
> > --- a/drivers/crypto/ccp/sev-dev.c
> > +++ b/drivers/crypto/ccp/sev-dev.c
> > @@ -742,6 +742,11 @@ static int sev_update_firmware(struct device *dev)
> >   	struct page *p;
> >   	u64 data_size;
> > +	if (!sev_version_greater_or_equal(0, 15)) {
> > +		dev_dbg(dev, "DOWNLOAD_FIRMWARE not supported\n");
> > +		return -1;
> > +	}
> > +
> >   	if (sev_get_firmware(dev, &firmware) == -ENOENT) {
> >   		dev_dbg(dev, "No SEV firmware file present\n");
> >   		return -1;
> > @@ -774,6 +779,14 @@ static int sev_update_firmware(struct device *dev)
> >   	data->len = firmware->size;
> >   	ret = sev_do_cmd(SEV_CMD_DOWNLOAD_FIRMWARE, data, &error);
> > +
> > +	/*
> > +	 * A quirk for fixing the committed TCB version, when upgrading from
> > +	 * earlier firmware version than 1.33.01.
> 
> s/1.33.01/1.50/
> 
> Thanks,
> Tom

Thanks Tom, I'll address the issues and send a new version.

BR, Jarkko