On Sat, Jul 19, 2014 at 12:27:21AM +0000, Kay, Allen M wrote:
> > For the MCH PCI registers that do need to be read - can you tell us which ones those are?
>
> In qemu/hw/xen_pt_igd.c/igd_pci_read(), following MCH PCI config register reads are passthrough to the host HW. Some of the registers are needed by Ironlake GFX driver which we probably can remove. I did a trace recently on Broadwell, the number of register accessed are even smaller (0, 2, 2c, 2e, 50, 52, a0, a4). Given that we now have integrated MCH and GPU in the same socket, looks like driver can easily remove reads for offsets 0 - 0x2e.
>
> case 0x00: /* vendor id */
> case 0x02: /* device id */
> case 0x08: /* revision id */
> case 0x2c: /* sybsystem vendor id */
> case 0x2e: /* sybsystem id */
Right. We can fix the i915 to use the mechanism that Michael mentioned.
(see attached RFC patches)
> case 0x50: /* SNB: processor graphics control register */
> case 0x52: /* processor graphics control register */
> case 0xa0: /* top of memory */
> case 0xb0: /* ILK: BSM: should read from dev 2 offset 0x5c */
> case 0x58: /* SNB: PAVPC Offset */
> case 0xa4: /* SNB: graphics base of stolen memory */
> case 0xa8: /* SNB: base of GTT stolen memory */
I dug in the intel-gtt.c (see ironlake_gtt_driver) to figure out this
a bit more. As in, I speculated, what if we returned 0 (and not implement
any support for reading from these registers). What would happen?
0x52 for Ironlake (g5):
------------------
It looks like intel_gmch_probe is called when i915_gem_gtt_init
starts (there is a lot of code that looks to be used between
intel-gtt.c and i915.c).
Anyhow the interesting parts are that i9xx_setup ends up calling
ioremap the i915 BAR to setup some of these registers for older generations.
Then i965_gtt_total_entries gets which reads 0x52, but it is only
needed for v5 generation. For other (v4 and G33) it reads it from the GPU's
0x2020 register.
If there is a mismatch, it writes to the GPU at 0x2020 to update the
the size based on the bridge. And then it reads from 0x2020 and that
is returned and stuck in intel_private.gtt_total_entries.
So 0x52 in the emulated bridge could be populated with what the
GPU has at 0x2020. And the writes go in the emulated area.
0x52 for v6 -> v8:
-----------------
We seem to go to gen6_gmch_probe which just figures out the
the GTT based on the GPU's BAR sizes. The stolen values
are read from 0x50 from the GPU. So no need to touch the bridge
(see gen6_gmch_probe)
OK, so no need to have 0x52 or 0x50 in the bridge.
0xA0:
---------
Could not find any reference in the Linux code. Why would
Windows driver need this? If we returned the _real_ TOM would
it matter? Is it used to figure out the device should use 32-bit
DMA operations or 40-bit?
0xb0 or 0x5c:
-------------
No mention of them in the Linux code.
0x58, 0xa4, 0xa8:
-----------------
No usage of them in the Linux code. We seem to be using the 0x52
from the bridge and 0x2020 from the GPU for this functionality.
So in theory*, if using Ironlake we need to have a proper value
in 0x52 in the bridge. But for the later chipsets we do not need
these values (I am assuming that intel_setup_mchbar can safely
return as it does that for Ironlake and could very well for later
generations).
Can this be reflected in the Windows driver as well?
P.S.
*theory: That is assuming we modify the Linux i915_drv.c:intel_detect_pch
to pick up the id as suggested earlier. See the RFC patches attached.
(Not compile tested at all!)
>
> Allen
>
> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx]
> Sent: Friday, July 18, 2014 6:45 AM
> To: Kay, Allen M
> Cc: Michael S. Tsirkin; Jesse Barnes; peter.maydell@xxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx; Ross Philipson; airlied@xxxxxxxx; daniel.vetter@xxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Kelly.Zytaruk@xxxxxxx; qemu-devel@xxxxxxxxxx; Anthony Perard; Stefano Stabellini; anthony@xxxxxxxxxxxxx; Paolo Bonzini; Zhang, Yang Z; Chen, Tiejun
> Subject: Re: ResettRe: [Xen-devel] [v5][PATCH 0/5] xen: add Intel IGD passthrough support
>
> On Thu, Jul 17, 2014 at 05:37:12PM +0000, Kay, Allen M wrote:
> > > That sounds great. Tiejun could you confirm that with windows driver guys too?
> >
> > I believe windows driver can also assume specific CPU/PCH combos. I will discuss this with native Windows driver guys. Preferably, the same code path can be used for both native and virtualization cases to avoid frequent breakage as most developers and QA do not test new code changes in virtualization environment.
> >
> > I have verified that Windows driver do not need to write to any MCH PCI registers on HSW/BDW so the PCI write function can be removed. The MCH PCI registers that need to be read, we are working with HW team to get them mirrored in GPU MMIO registers in future HW.
> >
>
> For the MCH PCI registers that do need to be read - can you tell us which ones those are?
>
> Thank you!
> > Allen
> >
> > -----Original Message-----
> > From: Intel-gfx [mailto:intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx] On
> > Behalf Of Michael S. Tsirkin
> > Sent: Thursday, July 03, 2014 1:28 PM
> > To: Jesse Barnes
> > Cc: peter.maydell@xxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx; Ross
> > Philipson; Konrad Rzeszutek Wilk; airlied@xxxxxxxx;
> > daniel.vetter@xxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx;
> > Kelly.Zytaruk@xxxxxxx; qemu-devel@xxxxxxxxxx; Anthony Perard; Stefano
> > Stabellini; anthony@xxxxxxxxxxxxx; Paolo Bonzini; Zhang, Yang Z; Chen,
> > Tiejun
> > Subject: Re: ResettRe: [Xen-devel] [v5][PATCH 0/5] xen:
> > add Intel IGD passthrough support
> >
> > On Thu, Jul 03, 2014 at 12:09:28PM -0700, Jesse Barnes wrote:
> > > On Thu, 3 Jul 2014 14:26:12 -0400
> > > Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> > >
> > > > On Thu, Jul 03, 2014 at 10:32:12AM +0300, Michael S. Tsirkin wrote:
> > > > > On Wed, Jul 02, 2014 at 12:23:37PM -0400, Konrad Rzeszutek Wilk wrote:
> > > > > > On Wed, Jul 02, 2014 at 04:50:15PM +0200, Paolo Bonzini wrote:
> > > > > > > Il 02/07/2014 16:00, Konrad Rzeszutek Wilk ha scritto:
> > > > > > > >With this long thread I lost a bit context about the
> > > > > > > >challenges that exists. But let me try summarizing it here
> > > > > > > >- which will hopefully get some consensus.
> > > > > > > >
> > > > > > > >1). Fix IGD hardware to not use Southbridge magic addresses.
> > > > > > > > We can moan and moan but I doubt it is going to change.
> > > > > > >
> > > > > > > There are two problems:
> > > > > > >
> > > > > > > - Northbridge (i.e. MCH i.e. PCI host bridge) configuration
> > > > > > > space addresses
> > > > > >
> > > > > > Right. So in drivers/gpu/drm/i915/i915_dma.c:
> > > > > > 1135 #define MCHBAR_I915 0x44
> > > > > > 1136 #define MCHBAR_I965 0x48
> > > > > >
> > > > > > 1147 int reg = INTEL_INFO(dev)->gen >= 4 ? MCHBAR_I965 : MCHBAR_I915;
> > > > > > 1152 if (INTEL_INFO(dev)->gen >= 4)
> > > > > > 1153 pci_read_config_dword(dev_priv->bridge_dev, reg + 4, &temp_hi);
> > > > > > 1154 pci_read_config_dword(dev_priv->bridge_dev, reg, &temp_lo);
> > > > > > 1155 mchbar_addr = ((u64)temp_hi << 32) | temp_lo;
> > > > > >
> > > > > > and
> > > > > >
> > > > > > 1139 #define DEVEN_REG 0x54
> > > > > >
> > > > > > 1193 int mchbar_reg = INTEL_INFO(dev)->gen >= 4 ? MCHBAR_I965 : MCHBAR_I915;
> > > > > > 1202 if (IS_I915G(dev) || IS_I915GM(dev)) {
> > > > > > 1203 pci_read_config_dword(dev_priv->bridge_dev, DEVEN_REG, &temp);
> > > > > > 1204 enabled = !!(temp & DEVEN_MCHBAR_EN);
> > > > > > 1205 } else {
> > > > > > 1206 pci_read_config_dword(dev_priv->bridge_dev, mchbar_reg, &temp);
> > > > > > 1207 enabled = temp & 1;
> > > > > > 1208 }
> > > > > > >
> > > > > > > - Southbridge (i.e. PCH i.e. ISA bridge) vendor/device ID;
> > > > > > > some versions of the driver identify it by class, some versions identify it by slot (1f.0).
> > > > > >
> > > > > > Right, So in drivers/gpu/drm/i915/i915_drv.c the giant
> > > > > > intel_detect_pch which sets the pch_type based on :
> > > > > >
> > > > > > 432 if (pch->vendor == PCI_VENDOR_ID_INTEL) {
> > > > > > 433 unsigned short id = pch->device & INTEL_PCH_DEVICE_ID_MASK;
> > > > > > 434 dev_priv->pch_id = id;
> > > > > > 435
> > > > > > 436 if (id == INTEL_PCH_IBX_DEVICE_ID_TYPE) {
> > > > > >
> > > > > > It checks for 0x3b00, 0x1c00, 0x1e00, 0x8c00 and 0x9c00.
> > > > > > The INTEL_PCH_DEVICE_ID_MASK is 0xff00
> > > > > > >
> > > > > > > To solve the first, make a new machine type, PIIX4-based,
> > > > > > > and pass through the registers you need. The patch must
> > > > > > > document _exactly_ why the registers are safe to pass. If
> > > > > > > they are not reserved on PIIX4, the patch must document what
> > > > > > > the same offsets mean on PIIX4, and why it's sensible to
> > > > > > > assume that firmware for virtual machine will not read/write them. Bonus point for also documenting the same for Q35.
> > > > > >
> > > > > > OK. They look to be related to setting up an MBAR , but I
> > > > > > don't understand why it is needed. Hopefully some of the i915 folks CC-ed here can answer.
> > > > >
> > > > > In particular, I think setting up MBAR should move out of i915
> > > > > and become the bridge driver tweak on linux and windows.
> > > >
> > > > That is an excellent idea.
> > > >
> > > > However I am still curious to _why_ it has to be done in the first place.
> > >
> > > The display part of the GPU is partly on the PCH, and it's possible
> > > to mix & match them a bit, so we have this detection code to figure
> > > things out. In some cases, the PCH display portion may not even be
> > > present, so we look for that too.
> > >
> > > Practically speaking, we could probably assume specific CPU/PCH
> > > combos, as I don't think they're generally mixed across generations,
> > > though SNB and IVB did have compatible sockets, so there is the
> > > possibility of mixing CPT and PPT PCHs, but those are register
> > > identical as far as the graphics driver is concerned, so even that should be safe.
> > >
> > > Beyond that, the other MCH data we need to look at is mirrored into
> > > the GPU's MMIO space on current gens. On older gens, we do need to
> > > poke at the memory controller a bit to get some info (see
> > > intel_setup_mchbar()), but that's not true of newer stuff. Looks
> > > like we only short circuit that on VLV though; we could probably do
> > > it on
> > > SNB+.
> >
> > That sounds great. Tiejun could you confirm that with windows driver guys too?
> >
> > > --
> > > Jesse Barnes, Intel Open Source Technology Center
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>From d82292c9fde0bd5ad04816096be3c4337660d4c7 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Wed, 23 Jul 2014 16:38:27 -0400
Subject: [PATCH 2/3] i915/drm/xen: Use subsystem_vendor and model instead of
bridge to figure type.
Instead of trying to figure out what type of i915 GPU it is
based on the bridge we will use the subsystem_device if it is
virtualized. The other benefit of this patch is that for
baremetal we can now remove the scanning of the bridge and
just use the GPU's PCI device to scan if we would like.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 404273b..11b6dc1 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -411,6 +411,9 @@ static int set_pch_type(struct pci_dev *pch, struct drm_i915_private *dev_priv)
if (pch->vendor != PCI_VENDOR_ID_INTEL)
return 0;
+ if (pch->subsystem_vendor == PCI_VENDOR_ID_XEN)
+ id = pch->subsystem_device & INTEL_PCH_DEVICE_ID_MASK;
+
dev_priv->pch_id = id;
if (id == INTEL_PCH_IBX_DEVICE_ID_TYPE) {
@@ -478,6 +481,14 @@ void intel_detect_pch(struct drm_device *dev)
if (ok)
break;
}
+ if (!ok) {
+ /*
+ * Try the GPU in case it is virtualized and we want to use
+ * the subsystem vendor id instead of the bridge to match.
+ */
+ pch = dev->pdev;
+ ok = set_pch_type(pch, dev_priv);
+ }
if (!ok)
DRM_DEBUG_KMS("No PCH found.\n");
}
--
1.9.3
>From 26d593b3b3255a57536aabc5cdf0f57061b6d888 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Wed, 23 Jul 2014 16:41:47 -0400
Subject: [PATCH 3/3] i915/drm/xen: If we are running under virtualized env we
don't need the bridge.
So lets check if the subsystem tells us that we are under Xen
and if so ignore the bridge.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_dma.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 6c65639..70bd61f 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1123,6 +1123,11 @@ static int i915_set_status_page(struct drm_device *dev, void *data,
static int i915_get_bridge_dev(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
+ struct pci_dev *pch = dev->pdev;
+
+ /* If we are virtualized we don't need the bridge. */
+ if (pch->subsystem_vendor == PCI_VENDOR_ID_XEN)
+ return 0;
dev_priv->bridge_dev = pci_get_bus_and_slot(0, PCI_DEVFN(0, 0));
if (!dev_priv->bridge_dev) {
@@ -1199,6 +1204,9 @@ intel_setup_mchbar(struct drm_device *dev)
dev_priv->mchbar_need_disable = false;
+ if (!dev_priv->bridge_dev)
+ return;
+
if (IS_I915G(dev) || IS_I915GM(dev)) {
pci_read_config_dword(dev_priv->bridge_dev, DEVEN_REG, &temp);
enabled = !!(temp & DEVEN_MCHBAR_EN);
@@ -1801,7 +1809,8 @@ out_regs:
intel_uncore_fini(dev);
pci_iounmap(dev->pdev, dev_priv->regs);
put_bridge:
- pci_dev_put(dev_priv->bridge_dev);
+ if (dev_priv->bridge_dev)
+ pci_dev_put(dev_priv->bridge_dev);
free_priv:
if (dev_priv->slab)
kmem_cache_destroy(dev_priv->slab);
@@ -1903,7 +1912,8 @@ int i915_driver_unload(struct drm_device *dev)
if (dev_priv->slab)
kmem_cache_destroy(dev_priv->slab);
- pci_dev_put(dev_priv->bridge_dev);
+ if (dev_priv->bridge_dev)
+ pci_dev_put(dev_priv->bridge_dev);
kfree(dev_priv);
return 0;
--
1.9.3
>From d692d0458f60e3207d7dba615c8cbbcdeca07187 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Wed, 23 Jul 2014 16:31:12 -0400
Subject: [PATCH 1/3] drm/i915: Move figuring out of the PCH type to its own
function and fix reference bug.
We move the figuring of the PCH type to its own function
and simplyfind the loop. Also we fix the 'pci_dev_put' which
previously was only called for the last bridge. Meaning
if the host had two bridges we would only put the last one, but
not the first one. With this we fix that.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.c | 90 ++++++++++++++++++++++-------------------
1 file changed, 49 insertions(+), 41 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 651e65e..404273b 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -404,11 +404,55 @@ static const struct pci_device_id pciidlist[] = { /* aka */
MODULE_DEVICE_TABLE(pci, pciidlist);
#endif
+static int set_pch_type(struct pci_dev *pch, struct drm_i915_private *dev_priv)
+{
+ unsigned short id = pch->device & INTEL_PCH_DEVICE_ID_MASK;
+
+ if (pch->vendor != PCI_VENDOR_ID_INTEL)
+ return 0;
+
+ dev_priv->pch_id = id;
+
+ if (id == INTEL_PCH_IBX_DEVICE_ID_TYPE) {
+ dev_priv->pch_type = PCH_IBX;
+ DRM_DEBUG_KMS("Found Ibex Peak PCH\n");
+ WARN_ON(!IS_GEN5(dev));
+ } else if (id == INTEL_PCH_CPT_DEVICE_ID_TYPE) {
+ dev_priv->pch_type = PCH_CPT;
+ DRM_DEBUG_KMS("Found CougarPoint PCH\n");
+ WARN_ON(!(IS_GEN6(dev) || IS_IVYBRIDGE(dev)));
+ } else if (id == INTEL_PCH_PPT_DEVICE_ID_TYPE) {
+ /* PantherPoint is CPT compatible */
+ dev_priv->pch_type = PCH_CPT;
+ DRM_DEBUG_KMS("Found PantherPoint PCH\n");
+ WARN_ON(!(IS_GEN6(dev) || IS_IVYBRIDGE(dev)));
+ } else if (id == INTEL_PCH_LPT_DEVICE_ID_TYPE) {
+ dev_priv->pch_type = PCH_LPT;
+ DRM_DEBUG_KMS("Found LynxPoint PCH\n");
+ WARN_ON(!IS_HASWELL(dev));
+ WARN_ON(IS_ULT(dev));
+ } else if (IS_BROADWELL(dev)) {
+ dev_priv->pch_type = PCH_LPT;
+ dev_priv->pch_id =
+ INTEL_PCH_LPT_LP_DEVICE_ID_TYPE;
+ DRM_DEBUG_KMS("This is Broadwell, assuming "
+ "LynxPoint LP PCH\n");
+ } else if (id == INTEL_PCH_LPT_LP_DEVICE_ID_TYPE) {
+ dev_priv->pch_type = PCH_LPT;
+ DRM_DEBUG_KMS("Found LynxPoint LP PCH\n");
+ WARN_ON(!IS_HASWELL(dev));
+ WARN_ON(!IS_ULT(dev));
+ } else
+ return 1;
+
+ return 1;
+}
+
void intel_detect_pch(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
struct pci_dev *pch = NULL;
-
+ int ok = 0;
/* In all current cases, num_pipes is equivalent to the PCH_NOP setting
* (which really amounts to a PCH but no South Display).
*/
@@ -429,49 +473,13 @@ void intel_detect_pch(struct drm_device *dev)
* of only checking the first one.
*/
while ((pch = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, pch))) {
- if (pch->vendor == PCI_VENDOR_ID_INTEL) {
- unsigned short id = pch->device & INTEL_PCH_DEVICE_ID_MASK;
- dev_priv->pch_id = id;
-
- if (id == INTEL_PCH_IBX_DEVICE_ID_TYPE) {
- dev_priv->pch_type = PCH_IBX;
- DRM_DEBUG_KMS("Found Ibex Peak PCH\n");
- WARN_ON(!IS_GEN5(dev));
- } else if (id == INTEL_PCH_CPT_DEVICE_ID_TYPE) {
- dev_priv->pch_type = PCH_CPT;
- DRM_DEBUG_KMS("Found CougarPoint PCH\n");
- WARN_ON(!(IS_GEN6(dev) || IS_IVYBRIDGE(dev)));
- } else if (id == INTEL_PCH_PPT_DEVICE_ID_TYPE) {
- /* PantherPoint is CPT compatible */
- dev_priv->pch_type = PCH_CPT;
- DRM_DEBUG_KMS("Found PantherPoint PCH\n");
- WARN_ON(!(IS_GEN6(dev) || IS_IVYBRIDGE(dev)));
- } else if (id == INTEL_PCH_LPT_DEVICE_ID_TYPE) {
- dev_priv->pch_type = PCH_LPT;
- DRM_DEBUG_KMS("Found LynxPoint PCH\n");
- WARN_ON(!IS_HASWELL(dev));
- WARN_ON(IS_ULT(dev));
- } else if (IS_BROADWELL(dev)) {
- dev_priv->pch_type = PCH_LPT;
- dev_priv->pch_id =
- INTEL_PCH_LPT_LP_DEVICE_ID_TYPE;
- DRM_DEBUG_KMS("This is Broadwell, assuming "
- "LynxPoint LP PCH\n");
- } else if (id == INTEL_PCH_LPT_LP_DEVICE_ID_TYPE) {
- dev_priv->pch_type = PCH_LPT;
- DRM_DEBUG_KMS("Found LynxPoint LP PCH\n");
- WARN_ON(!IS_HASWELL(dev));
- WARN_ON(!IS_ULT(dev));
- } else
- continue;
-
+ ok = set_pch_type(pch, dev_priv);
+ pci_dev_put(pch);
+ if (ok)
break;
- }
}
- if (!pch)
+ if (!ok)
DRM_DEBUG_KMS("No PCH found.\n");
-
- pci_dev_put(pch);
}
bool i915_semaphore_is_enabled(struct drm_device *dev)
--
1.9.3
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