Re: [PATCH 3/5 V2] tpm2: add longer timeouts for creation commands.

[Jarkko Sakkinen]

On Tue, 2018-03-06 at 15:19 +, Winkler, Tomas wrote:
> > On Tue, 2018-03-06 at 11:25 +0200, Tomas Winkler wrote:
> > > TPM2_CC_Create(0x153) and TPM2_CC_CreatePrimary (0x131) involve
> > > generation of crypto keys which can be a computationally intensive task.
> > > The timeout is set to 3min.
> > > Rather than increasing default timeout a new constant is added, to not
> > > stall for too long on regular commands failures.
> > > 
> > > Signed-off-by: Tomas Winkler 
> > 
> > Why are you radically chaging the default timeout? The commit message
> > does not tell anything about that change.
> > 
> 
> Let me, recheck but it should be same value just converted to msecs.
>  
> > Why couldn't we just have two timeouts: one default and one long that
> > would be at least as long as the longest timeout defined in the spec?
> 
> I've tried to explain it in the commit message but apparently has failed. 
> 
> We have a default or undefined which should be the same as it was unless I did
> some silly mistake in conversion to msecs (will check), ass all others are in
> msecs.
> It was 2 min = 2 * 60 * HZ (in jiffies) which would be msecs_to_jiffies(2 * 60
> * 1000 = 12) 
> TPM2_DURATION_DEFAULT   = 12

Aah, of course :-) The problem was that I had somehow a blid spot with
seeing the msec_to_jiffies() conversion.

TPM_NUM_DURATIONS would a better name than TPM_DURATION_MAX because
TPM_DURATION_MAX is easy to confuse with TPM_DURATION_* constants.

/Jarkko

Re: [PATCH 3/5 V2] tpm2: add longer timeouts for creation commands.

[Jarkko Sakkinen]

On Tue, 2018-03-06 at 15:19 +, Winkler, Tomas wrote:
> > On Tue, 2018-03-06 at 11:25 +0200, Tomas Winkler wrote:
> > > TPM2_CC_Create(0x153) and TPM2_CC_CreatePrimary (0x131) involve
> > > generation of crypto keys which can be a computationally intensive task.
> > > The timeout is set to 3min.
> > > Rather than increasing default timeout a new constant is added, to not
> > > stall for too long on regular commands failures.
> > > 
> > > Signed-off-by: Tomas Winkler 
> > 
> > Why are you radically chaging the default timeout? The commit message
> > does not tell anything about that change.
> > 
> 
> Let me, recheck but it should be same value just converted to msecs.
>  
> > Why couldn't we just have two timeouts: one default and one long that
> > would be at least as long as the longest timeout defined in the spec?
> 
> I've tried to explain it in the commit message but apparently has failed. 
> 
> We have a default or undefined which should be the same as it was unless I did
> some silly mistake in conversion to msecs (will check), ass all others are in
> msecs.
> It was 2 min = 2 * 60 * HZ (in jiffies) which would be msecs_to_jiffies(2 * 60
> * 1000 = 12) 
> TPM2_DURATION_DEFAULT   = 12

Aah, of course :-) The problem was that I had somehow a blid spot with
seeing the msec_to_jiffies() conversion.

TPM_NUM_DURATIONS would a better name than TPM_DURATION_MAX because
TPM_DURATION_MAX is easy to confuse with TPM_DURATION_* constants.

/Jarkko

RE: [PATCH 3/5 V2] tpm2: add longer timeouts for creation commands.

[Winkler, Tomas]

> On Tue, 2018-03-06 at 11:25 +0200, Tomas Winkler wrote:
> > TPM2_CC_Create(0x153) and TPM2_CC_CreatePrimary (0x131) involve
> > generation of crypto keys which can be a computationally intensive task.
> > The timeout is set to 3min.
> > Rather than increasing default timeout a new constant is added, to not
> > stall for too long on regular commands failures.
> >
> > Signed-off-by: Tomas Winkler 
> 
> Why are you radically chaging the default timeout? The commit message
> does not tell anything about that change.
>
Let me, recheck but it should be same value just converted to msecs.
 
> Why couldn't we just have two timeouts: one default and one long that
> would be at least as long as the longest timeout defined in the spec?

I've tried to explain it in the commit message but apparently has failed. 

We have a default or undefined which should be the same as it was unless I did 
some silly mistake in conversion to msecs (will check), ass all others are in 
msecs.
It was 2 min = 2 * 60 * HZ (in jiffies) which would be msecs_to_jiffies(2 * 60 
* 1000 = 12) 
TPM2_DURATION_DEFAULT   = 12

Then we have a new one which is 3 min just for key generation (Prime number 
generation is heavy liffting) 

> Then we would not have to ever update LAST_CC constant, we could actually
> remove it completely.

I believe I've removed it next patch, I didn’t want do too much in this one.

Thanks
Tomas

RE: [PATCH 3/5 V2] tpm2: add longer timeouts for creation commands.

[Winkler, Tomas]

> On Tue, 2018-03-06 at 11:25 +0200, Tomas Winkler wrote:
> > TPM2_CC_Create(0x153) and TPM2_CC_CreatePrimary (0x131) involve
> > generation of crypto keys which can be a computationally intensive task.
> > The timeout is set to 3min.
> > Rather than increasing default timeout a new constant is added, to not
> > stall for too long on regular commands failures.
> >
> > Signed-off-by: Tomas Winkler 
> 
> Why are you radically chaging the default timeout? The commit message
> does not tell anything about that change.
>
Let me, recheck but it should be same value just converted to msecs.
 
> Why couldn't we just have two timeouts: one default and one long that
> would be at least as long as the longest timeout defined in the spec?

I've tried to explain it in the commit message but apparently has failed. 

We have a default or undefined which should be the same as it was unless I did 
some silly mistake in conversion to msecs (will check), ass all others are in 
msecs.
It was 2 min = 2 * 60 * HZ (in jiffies) which would be msecs_to_jiffies(2 * 60 
* 1000 = 12) 
TPM2_DURATION_DEFAULT   = 12

Then we have a new one which is 3 min just for key generation (Prime number 
generation is heavy liffting) 

> Then we would not have to ever update LAST_CC constant, we could actually
> remove it completely.

I believe I've removed it next patch, I didn’t want do too much in this one.

Thanks
Tomas

Re: [PATCH 3/5 V2] tpm2: add longer timeouts for creation commands.

[Jarkko Sakkinen]

On Tue, 2018-03-06 at 11:25 +0200, Tomas Winkler wrote:
> TPM2_CC_Create(0x153) and TPM2_CC_CreatePrimary (0x131) involve generation
> of crypto keys which can be a computationally intensive task.
> The timeout is set to 3min.
> Rather than increasing default timeout a new constant is
> added, to not stall for too long on regular commands failures.
> 
> Signed-off-by: Tomas Winkler 

Why are you radically chaging the default timeout? The commit
message does not tell anything about that change.

Why couldn't we just have two timeouts: one default and one long that
would be at least as long as the longest timeout defined in the spec?
Then we would not have to ever update LAST_CC constant, we could
actually remove it completely.

/Jarkko

Re: [PATCH 3/5 V2] tpm2: add longer timeouts for creation commands.

[Jarkko Sakkinen]

On Tue, 2018-03-06 at 11:25 +0200, Tomas Winkler wrote:
> TPM2_CC_Create(0x153) and TPM2_CC_CreatePrimary (0x131) involve generation
> of crypto keys which can be a computationally intensive task.
> The timeout is set to 3min.
> Rather than increasing default timeout a new constant is
> added, to not stall for too long on regular commands failures.
> 
> Signed-off-by: Tomas Winkler 

Why are you radically chaging the default timeout? The commit
message does not tell anything about that change.

Why couldn't we just have two timeouts: one default and one long that
would be at least as long as the longest timeout defined in the spec?
Then we would not have to ever update LAST_CC constant, we could
actually remove it completely.

/Jarkko