Re: [Qemu-devel] [PATCH] ahci: advertise HOST_CAP_64

2017-01-31 Thread Ladi Prosek 
On Tue, Jan 31, 2017 at 1:56 PM, John Snow  wrote:
>
>
> On 01/16/2017 02:49 AM, Ladi Prosek wrote:
>> On Fri, Jan 13, 2017 at 8:15 PM, John Snow  wrote:
>>>
>>>
>>> On 01/13/2017 02:01 PM, Ladi Prosek wrote:
 On Fri, Jan 13, 2017 at 7:31 PM, John Snow  wrote:
>
>
> On 01/13/2017 01:12 PM, Ladi Prosek wrote:
>> On Fri, Jan 13, 2017 at 6:23 PM, John Snow  wrote:
>>> On 01/13/2017 06:02 AM, Ladi Prosek wrote:
 The AHCI emulation code supports 64-bit addressing and should 
 advertise this
 fact in the Host Capabilities register. Both Linux and Windows drivers 
 test
 this bit to decide if the upper 32 bits of various registers may be 
 written
 to, and at least some versions of Windows have a bug where DMA is 
 attempted
 with an address above 4GB but, in the absence of HOST_CAP_64, the 
 upper 32
 bits are left unititialized which leads to a memory corruption.

 Signed-off-by: Ladi Prosek 
 ---
  hw/ide/ahci.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

 diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
 index 3c19bda..6a17acf 100644
 --- a/hw/ide/ahci.c
 +++ b/hw/ide/ahci.c
 @@ -488,7 +488,7 @@ static void ahci_reg_init(AHCIState *s)
  s->control_regs.cap = (s->ports - 1) |
(AHCI_NUM_COMMAND_SLOTS << 8) |
(AHCI_SUPPORTED_SPEED_GEN1 << 
 AHCI_SUPPORTED_SPEED) |
 -  HOST_CAP_NCQ | HOST_CAP_AHCI;
 +  HOST_CAP_NCQ | HOST_CAP_AHCI | HOST_CAP_64;

  s->control_regs.impl = (1 << s->ports) - 1;


>>>
>>> Was this tested? What was the use case that prompted this patch, and do
>>> you have a public bugzilla to point to?
>>
>> Sorry, I thought you were aware. Here's the BZ with details:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1411105
>>
>
> It's for the public record :)
>
> I'm going to amend your commit message, OK?
>
> https://github.com/jnsnow/qemu/commit/f037be92fc0c4580b846134e0355a69d0eccd0d9

 Minor nit: the OS we know for sure is affected is Windows Server 2008,
 without the "R2". Thanks!

>>>
>>> I misunderstood. It looked like the initial report was for "SP2," though
>>> I see you saying that the R2 version actually worked okay, but by
>>> coincidence.
>>>
>>> I didn't think there *was* an "SP2," for Windows Server, so I
>>> interpreted that to mean R2.
>>>
>>> So this only manifests with vanilla 2008?
>>
>> We know it manifests on 2008 SP2, which is very different from 2008
>> R2. 2008 is the server variant of Vista, 2008 R2 is the server variant
>> of Win7 (yay for marketing names!)
>>
>> I believe that 2008 SP2 32-bit is the only OS where it's been confirmed so 
>> far.
>>
>
> Thanks for clearing that up for me, I re-edited the commit message
> upstream. If it looks OK, I'll likely merge this when I get back home
> after FOSDEM.

Looks good, thanks!

> --js

Re: [Qemu-devel] [PATCH] ahci: advertise HOST_CAP_64

2017-01-31 Thread John Snow 


On 01/16/2017 02:49 AM, Ladi Prosek wrote:
> On Fri, Jan 13, 2017 at 8:15 PM, John Snow  wrote:
>>
>>
>> On 01/13/2017 02:01 PM, Ladi Prosek wrote:
>>> On Fri, Jan 13, 2017 at 7:31 PM, John Snow  wrote:


 On 01/13/2017 01:12 PM, Ladi Prosek wrote:
> On Fri, Jan 13, 2017 at 6:23 PM, John Snow  wrote:
>> On 01/13/2017 06:02 AM, Ladi Prosek wrote:
>>> The AHCI emulation code supports 64-bit addressing and should advertise 
>>> this
>>> fact in the Host Capabilities register. Both Linux and Windows drivers 
>>> test
>>> this bit to decide if the upper 32 bits of various registers may be 
>>> written
>>> to, and at least some versions of Windows have a bug where DMA is 
>>> attempted
>>> with an address above 4GB but, in the absence of HOST_CAP_64, the upper 
>>> 32
>>> bits are left unititialized which leads to a memory corruption.
>>>
>>> Signed-off-by: Ladi Prosek 
>>> ---
>>>  hw/ide/ahci.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
>>> index 3c19bda..6a17acf 100644
>>> --- a/hw/ide/ahci.c
>>> +++ b/hw/ide/ahci.c
>>> @@ -488,7 +488,7 @@ static void ahci_reg_init(AHCIState *s)
>>>  s->control_regs.cap = (s->ports - 1) |
>>>(AHCI_NUM_COMMAND_SLOTS << 8) |
>>>(AHCI_SUPPORTED_SPEED_GEN1 << 
>>> AHCI_SUPPORTED_SPEED) |
>>> -  HOST_CAP_NCQ | HOST_CAP_AHCI;
>>> +  HOST_CAP_NCQ | HOST_CAP_AHCI | HOST_CAP_64;
>>>
>>>  s->control_regs.impl = (1 << s->ports) - 1;
>>>
>>>
>>
>> Was this tested? What was the use case that prompted this patch, and do
>> you have a public bugzilla to point to?
>
> Sorry, I thought you were aware. Here's the BZ with details:
> https://bugzilla.redhat.com/show_bug.cgi?id=1411105
>

 It's for the public record :)

 I'm going to amend your commit message, OK?

 https://github.com/jnsnow/qemu/commit/f037be92fc0c4580b846134e0355a69d0eccd0d9
>>>
>>> Minor nit: the OS we know for sure is affected is Windows Server 2008,
>>> without the "R2". Thanks!
>>>
>>
>> I misunderstood. It looked like the initial report was for "SP2," though
>> I see you saying that the R2 version actually worked okay, but by
>> coincidence.
>>
>> I didn't think there *was* an "SP2," for Windows Server, so I
>> interpreted that to mean R2.
>>
>> So this only manifests with vanilla 2008?
> 
> We know it manifests on 2008 SP2, which is very different from 2008
> R2. 2008 is the server variant of Vista, 2008 R2 is the server variant
> of Win7 (yay for marketing names!)
> 
> I believe that 2008 SP2 32-bit is the only OS where it's been confirmed so 
> far.
> 

Thanks for clearing that up for me, I re-edited the commit message
upstream. If it looks OK, I'll likely merge this when I get back home
after FOSDEM.

--js

Re: [Qemu-devel] [PATCH] ahci: advertise HOST_CAP_64

2017-01-15 Thread Ladi Prosek 
On Fri, Jan 13, 2017 at 8:15 PM, John Snow  wrote:
>
>
> On 01/13/2017 02:01 PM, Ladi Prosek wrote:
>> On Fri, Jan 13, 2017 at 7:31 PM, John Snow  wrote:
>>>
>>>
>>> On 01/13/2017 01:12 PM, Ladi Prosek wrote:
 On Fri, Jan 13, 2017 at 6:23 PM, John Snow  wrote:
> On 01/13/2017 06:02 AM, Ladi Prosek wrote:
>> The AHCI emulation code supports 64-bit addressing and should advertise 
>> this
>> fact in the Host Capabilities register. Both Linux and Windows drivers 
>> test
>> this bit to decide if the upper 32 bits of various registers may be 
>> written
>> to, and at least some versions of Windows have a bug where DMA is 
>> attempted
>> with an address above 4GB but, in the absence of HOST_CAP_64, the upper 
>> 32
>> bits are left unititialized which leads to a memory corruption.
>>
>> Signed-off-by: Ladi Prosek 
>> ---
>>  hw/ide/ahci.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
>> index 3c19bda..6a17acf 100644
>> --- a/hw/ide/ahci.c
>> +++ b/hw/ide/ahci.c
>> @@ -488,7 +488,7 @@ static void ahci_reg_init(AHCIState *s)
>>  s->control_regs.cap = (s->ports - 1) |
>>(AHCI_NUM_COMMAND_SLOTS << 8) |
>>(AHCI_SUPPORTED_SPEED_GEN1 << 
>> AHCI_SUPPORTED_SPEED) |
>> -  HOST_CAP_NCQ | HOST_CAP_AHCI;
>> +  HOST_CAP_NCQ | HOST_CAP_AHCI | HOST_CAP_64;
>>
>>  s->control_regs.impl = (1 << s->ports) - 1;
>>
>>
>
> Was this tested? What was the use case that prompted this patch, and do
> you have a public bugzilla to point to?

 Sorry, I thought you were aware. Here's the BZ with details:
 https://bugzilla.redhat.com/show_bug.cgi?id=1411105

>>>
>>> It's for the public record :)
>>>
>>> I'm going to amend your commit message, OK?
>>>
>>> https://github.com/jnsnow/qemu/commit/f037be92fc0c4580b846134e0355a69d0eccd0d9
>>
>> Minor nit: the OS we know for sure is affected is Windows Server 2008,
>> without the "R2". Thanks!
>>
>
> I misunderstood. It looked like the initial report was for "SP2," though
> I see you saying that the R2 version actually worked okay, but by
> coincidence.
>
> I didn't think there *was* an "SP2," for Windows Server, so I
> interpreted that to mean R2.
>
> So this only manifests with vanilla 2008?

We know it manifests on 2008 SP2, which is very different from 2008
R2. 2008 is the server variant of Vista, 2008 R2 is the server variant
of Win7 (yay for marketing names!)

I believe that 2008 SP2 32-bit is the only OS where it's been confirmed so far.

 In short, Windows guests run into issues in certain virtual HW
 configurations if the bit is not set. I have tested the patch and
 verified that it fixes the failing cases.

>>>
>>> Great. I'm CCing qemu-stable as this should probably be included in
>>> 2.7.2 / 2.8.1 / etc.
>>>
> It looks correct via the spec, thank you for finding this oversight. It
> looks like everywhere this bit would make a difference we already do the
> correct thing for having this bit set.
>
> From what I can gather from the spec, it looks as if even 32bit guests
> must ensure that the upper 32bit registers are cleared, so I think we're
> all set here.
>
> Reviewed-by: John Snow 
>>>
>>> Thanks, applied to my IDE tree:
>>>
>>> https://github.com/jnsnow/qemu/commits/ide
>>> https://github.com/jnsnow/qemu.git
>>>
>>> --js

Re: [Qemu-devel] [PATCH] ahci: advertise HOST_CAP_64

2017-01-13 Thread John Snow 


On 01/13/2017 02:01 PM, Ladi Prosek wrote:
> On Fri, Jan 13, 2017 at 7:31 PM, John Snow  wrote:
>>
>>
>> On 01/13/2017 01:12 PM, Ladi Prosek wrote:
>>> On Fri, Jan 13, 2017 at 6:23 PM, John Snow  wrote:
 On 01/13/2017 06:02 AM, Ladi Prosek wrote:
> The AHCI emulation code supports 64-bit addressing and should advertise 
> this
> fact in the Host Capabilities register. Both Linux and Windows drivers 
> test
> this bit to decide if the upper 32 bits of various registers may be 
> written
> to, and at least some versions of Windows have a bug where DMA is 
> attempted
> with an address above 4GB but, in the absence of HOST_CAP_64, the upper 32
> bits are left unititialized which leads to a memory corruption.
>
> Signed-off-by: Ladi Prosek 
> ---
>  hw/ide/ahci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
> index 3c19bda..6a17acf 100644
> --- a/hw/ide/ahci.c
> +++ b/hw/ide/ahci.c
> @@ -488,7 +488,7 @@ static void ahci_reg_init(AHCIState *s)
>  s->control_regs.cap = (s->ports - 1) |
>(AHCI_NUM_COMMAND_SLOTS << 8) |
>(AHCI_SUPPORTED_SPEED_GEN1 << 
> AHCI_SUPPORTED_SPEED) |
> -  HOST_CAP_NCQ | HOST_CAP_AHCI;
> +  HOST_CAP_NCQ | HOST_CAP_AHCI | HOST_CAP_64;
>
>  s->control_regs.impl = (1 << s->ports) - 1;
>
>

 Was this tested? What was the use case that prompted this patch, and do
 you have a public bugzilla to point to?
>>>
>>> Sorry, I thought you were aware. Here's the BZ with details:
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1411105
>>>
>>
>> It's for the public record :)
>>
>> I'm going to amend your commit message, OK?
>>
>> https://github.com/jnsnow/qemu/commit/f037be92fc0c4580b846134e0355a69d0eccd0d9
> 
> Minor nit: the OS we know for sure is affected is Windows Server 2008,
> without the "R2". Thanks!
> 

I misunderstood. It looked like the initial report was for "SP2," though
I see you saying that the R2 version actually worked okay, but by
coincidence.

I didn't think there *was* an "SP2," for Windows Server, so I
interpreted that to mean R2.

So this only manifests with vanilla 2008?

>>> In short, Windows guests run into issues in certain virtual HW
>>> configurations if the bit is not set. I have tested the patch and
>>> verified that it fixes the failing cases.
>>>
>>
>> Great. I'm CCing qemu-stable as this should probably be included in
>> 2.7.2 / 2.8.1 / etc.
>>
 It looks correct via the spec, thank you for finding this oversight. It
 looks like everywhere this bit would make a difference we already do the
 correct thing for having this bit set.

 From what I can gather from the spec, it looks as if even 32bit guests
 must ensure that the upper 32bit registers are cleared, so I think we're
 all set here.

 Reviewed-by: John Snow 
>>
>> Thanks, applied to my IDE tree:
>>
>> https://github.com/jnsnow/qemu/commits/ide
>> https://github.com/jnsnow/qemu.git
>>
>> --js

Re: [Qemu-devel] [PATCH] ahci: advertise HOST_CAP_64

2017-01-13 Thread Ladi Prosek 
On Fri, Jan 13, 2017 at 7:31 PM, John Snow  wrote:
>
>
> On 01/13/2017 01:12 PM, Ladi Prosek wrote:
>> On Fri, Jan 13, 2017 at 6:23 PM, John Snow  wrote:
>>> On 01/13/2017 06:02 AM, Ladi Prosek wrote:
 The AHCI emulation code supports 64-bit addressing and should advertise 
 this
 fact in the Host Capabilities register. Both Linux and Windows drivers test
 this bit to decide if the upper 32 bits of various registers may be written
 to, and at least some versions of Windows have a bug where DMA is attempted
 with an address above 4GB but, in the absence of HOST_CAP_64, the upper 32
 bits are left unititialized which leads to a memory corruption.

 Signed-off-by: Ladi Prosek 
 ---
  hw/ide/ahci.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

 diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
 index 3c19bda..6a17acf 100644
 --- a/hw/ide/ahci.c
 +++ b/hw/ide/ahci.c
 @@ -488,7 +488,7 @@ static void ahci_reg_init(AHCIState *s)
  s->control_regs.cap = (s->ports - 1) |
(AHCI_NUM_COMMAND_SLOTS << 8) |
(AHCI_SUPPORTED_SPEED_GEN1 << 
 AHCI_SUPPORTED_SPEED) |
 -  HOST_CAP_NCQ | HOST_CAP_AHCI;
 +  HOST_CAP_NCQ | HOST_CAP_AHCI | HOST_CAP_64;

  s->control_regs.impl = (1 << s->ports) - 1;


>>>
>>> Was this tested? What was the use case that prompted this patch, and do
>>> you have a public bugzilla to point to?
>>
>> Sorry, I thought you were aware. Here's the BZ with details:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1411105
>>
>
> It's for the public record :)
>
> I'm going to amend your commit message, OK?
>
> https://github.com/jnsnow/qemu/commit/f037be92fc0c4580b846134e0355a69d0eccd0d9

Minor nit: the OS we know for sure is affected is Windows Server 2008,
without the "R2". Thanks!

>> In short, Windows guests run into issues in certain virtual HW
>> configurations if the bit is not set. I have tested the patch and
>> verified that it fixes the failing cases.
>>
>
> Great. I'm CCing qemu-stable as this should probably be included in
> 2.7.2 / 2.8.1 / etc.
>
>>> It looks correct via the spec, thank you for finding this oversight. It
>>> looks like everywhere this bit would make a difference we already do the
>>> correct thing for having this bit set.
>>>
>>> From what I can gather from the spec, it looks as if even 32bit guests
>>> must ensure that the upper 32bit registers are cleared, so I think we're
>>> all set here.
>>>
>>> Reviewed-by: John Snow 
>
> Thanks, applied to my IDE tree:
>
> https://github.com/jnsnow/qemu/commits/ide
> https://github.com/jnsnow/qemu.git
>
> --js

Re: [Qemu-devel] [PATCH] ahci: advertise HOST_CAP_64

2017-01-13 Thread John Snow 


On 01/13/2017 01:12 PM, Ladi Prosek wrote:
> On Fri, Jan 13, 2017 at 6:23 PM, John Snow  wrote:
>> On 01/13/2017 06:02 AM, Ladi Prosek wrote:
>>> The AHCI emulation code supports 64-bit addressing and should advertise this
>>> fact in the Host Capabilities register. Both Linux and Windows drivers test
>>> this bit to decide if the upper 32 bits of various registers may be written
>>> to, and at least some versions of Windows have a bug where DMA is attempted
>>> with an address above 4GB but, in the absence of HOST_CAP_64, the upper 32
>>> bits are left unititialized which leads to a memory corruption.
>>>
>>> Signed-off-by: Ladi Prosek 
>>> ---
>>>  hw/ide/ahci.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
>>> index 3c19bda..6a17acf 100644
>>> --- a/hw/ide/ahci.c
>>> +++ b/hw/ide/ahci.c
>>> @@ -488,7 +488,7 @@ static void ahci_reg_init(AHCIState *s)
>>>  s->control_regs.cap = (s->ports - 1) |
>>>(AHCI_NUM_COMMAND_SLOTS << 8) |
>>>(AHCI_SUPPORTED_SPEED_GEN1 << 
>>> AHCI_SUPPORTED_SPEED) |
>>> -  HOST_CAP_NCQ | HOST_CAP_AHCI;
>>> +  HOST_CAP_NCQ | HOST_CAP_AHCI | HOST_CAP_64;
>>>
>>>  s->control_regs.impl = (1 << s->ports) - 1;
>>>
>>>
>>
>> Was this tested? What was the use case that prompted this patch, and do
>> you have a public bugzilla to point to?
> 
> Sorry, I thought you were aware. Here's the BZ with details:
> https://bugzilla.redhat.com/show_bug.cgi?id=1411105
> 

It's for the public record :)

I'm going to amend your commit message, OK?

https://github.com/jnsnow/qemu/commit/f037be92fc0c4580b846134e0355a69d0eccd0d9

> In short, Windows guests run into issues in certain virtual HW
> configurations if the bit is not set. I have tested the patch and
> verified that it fixes the failing cases.
> 

Great. I'm CCing qemu-stable as this should probably be included in
2.7.2 / 2.8.1 / etc.

>> It looks correct via the spec, thank you for finding this oversight. It
>> looks like everywhere this bit would make a difference we already do the
>> correct thing for having this bit set.
>>
>> From what I can gather from the spec, it looks as if even 32bit guests
>> must ensure that the upper 32bit registers are cleared, so I think we're
>> all set here.
>>
>> Reviewed-by: John Snow 

Thanks, applied to my IDE tree:

https://github.com/jnsnow/qemu/commits/ide
https://github.com/jnsnow/qemu.git

--js

Re: [Qemu-devel] [PATCH] ahci: advertise HOST_CAP_64

2017-01-13 Thread Ladi Prosek 
On Fri, Jan 13, 2017 at 6:23 PM, John Snow  wrote:
> On 01/13/2017 06:02 AM, Ladi Prosek wrote:
>> The AHCI emulation code supports 64-bit addressing and should advertise this
>> fact in the Host Capabilities register. Both Linux and Windows drivers test
>> this bit to decide if the upper 32 bits of various registers may be written
>> to, and at least some versions of Windows have a bug where DMA is attempted
>> with an address above 4GB but, in the absence of HOST_CAP_64, the upper 32
>> bits are left unititialized which leads to a memory corruption.
>>
>> Signed-off-by: Ladi Prosek 
>> ---
>>  hw/ide/ahci.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
>> index 3c19bda..6a17acf 100644
>> --- a/hw/ide/ahci.c
>> +++ b/hw/ide/ahci.c
>> @@ -488,7 +488,7 @@ static void ahci_reg_init(AHCIState *s)
>>  s->control_regs.cap = (s->ports - 1) |
>>(AHCI_NUM_COMMAND_SLOTS << 8) |
>>(AHCI_SUPPORTED_SPEED_GEN1 << 
>> AHCI_SUPPORTED_SPEED) |
>> -  HOST_CAP_NCQ | HOST_CAP_AHCI;
>> +  HOST_CAP_NCQ | HOST_CAP_AHCI | HOST_CAP_64;
>>
>>  s->control_regs.impl = (1 << s->ports) - 1;
>>
>>
>
> Was this tested? What was the use case that prompted this patch, and do
> you have a public bugzilla to point to?

Sorry, I thought you were aware. Here's the BZ with details:
https://bugzilla.redhat.com/show_bug.cgi?id=1411105

In short, Windows guests run into issues in certain virtual HW
configurations if the bit is not set. I have tested the patch and
verified that it fixes the failing cases.

> It looks correct via the spec, thank you for finding this oversight. It
> looks like everywhere this bit would make a difference we already do the
> correct thing for having this bit set.
>
> From what I can gather from the spec, it looks as if even 32bit guests
> must ensure that the upper 32bit registers are cleared, so I think we're
> all set here.
>
> Reviewed-by: John Snow

Re: [Qemu-devel] [PATCH] ahci: advertise HOST_CAP_64

2017-01-13 Thread John Snow 
On 01/13/2017 06:02 AM, Ladi Prosek wrote:
> The AHCI emulation code supports 64-bit addressing and should advertise this
> fact in the Host Capabilities register. Both Linux and Windows drivers test
> this bit to decide if the upper 32 bits of various registers may be written
> to, and at least some versions of Windows have a bug where DMA is attempted
> with an address above 4GB but, in the absence of HOST_CAP_64, the upper 32
> bits are left unititialized which leads to a memory corruption.
> 
> Signed-off-by: Ladi Prosek 
> ---
>  hw/ide/ahci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
> index 3c19bda..6a17acf 100644
> --- a/hw/ide/ahci.c
> +++ b/hw/ide/ahci.c
> @@ -488,7 +488,7 @@ static void ahci_reg_init(AHCIState *s)
>  s->control_regs.cap = (s->ports - 1) |
>(AHCI_NUM_COMMAND_SLOTS << 8) |
>(AHCI_SUPPORTED_SPEED_GEN1 << 
> AHCI_SUPPORTED_SPEED) |
> -  HOST_CAP_NCQ | HOST_CAP_AHCI;
> +  HOST_CAP_NCQ | HOST_CAP_AHCI | HOST_CAP_64;
>  
>  s->control_regs.impl = (1 << s->ports) - 1;
>  
> 

Was this tested? What was the use case that prompted this patch, and do
you have a public bugzilla to point to?

It looks correct via the spec, thank you for finding this oversight. It
looks like everywhere this bit would make a difference we already do the
correct thing for having this bit set.

>From what I can gather from the spec, it looks as if even 32bit guests
must ensure that the upper 32bit registers are cleared, so I think we're
all set here.

Reviewed-by: John Snow

[Qemu-devel] [PATCH] ahci: advertise HOST_CAP_64

2017-01-13 Thread Ladi Prosek 
The AHCI emulation code supports 64-bit addressing and should advertise this
fact in the Host Capabilities register. Both Linux and Windows drivers test
this bit to decide if the upper 32 bits of various registers may be written
to, and at least some versions of Windows have a bug where DMA is attempted
with an address above 4GB but, in the absence of HOST_CAP_64, the upper 32
bits are left unititialized which leads to a memory corruption.

Signed-off-by: Ladi Prosek 
---
 hw/ide/ahci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
index 3c19bda..6a17acf 100644
--- a/hw/ide/ahci.c
+++ b/hw/ide/ahci.c
@@ -488,7 +488,7 @@ static void ahci_reg_init(AHCIState *s)
 s->control_regs.cap = (s->ports - 1) |
   (AHCI_NUM_COMMAND_SLOTS << 8) |
   (AHCI_SUPPORTED_SPEED_GEN1 << AHCI_SUPPORTED_SPEED) |
-  HOST_CAP_NCQ | HOST_CAP_AHCI;
+  HOST_CAP_NCQ | HOST_CAP_AHCI | HOST_CAP_64;
 
 s->control_regs.impl = (1 << s->ports) - 1;
 
-- 
2.7.4