Alexandre Courbot
2025-Sep-03 10:44 UTC
[PATCH v3 02/11] gpu: nova-core: move GSP boot code out of `Gpu` constructor
On Wed Sep 3, 2025 at 5:26 PM JST, Danilo Krummrich wrote:> On Wed Sep 3, 2025 at 9:08 AM CEST, Alexandre Courbot wrote: >> On Wed Sep 3, 2025 at 4:53 AM JST, Danilo Krummrich wrote: >>> On Tue Sep 2, 2025 at 4:31 PM CEST, Alexandre Courbot wrote: >>>> diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs >>>> index 274989ea1fb4a5e3e6678a08920ddc76d2809ab2..1062014c0a488e959379f009c2e8029ffaa1e2f8 100644 >>>> --- a/drivers/gpu/nova-core/driver.rs >>>> +++ b/drivers/gpu/nova-core/driver.rs >>>> @@ -6,6 +6,8 @@ >>>> >>>> #[pin_data] >>>> pub(crate) struct NovaCore { >>>> + // Placeholder for the real `Gsp` object once it is built. >>>> + pub(crate) gsp: (), >>>> #[pin] >>>> pub(crate) gpu: Gpu, >>>> _reg: auxiliary::Registration, >>>> @@ -40,8 +42,14 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> Result<Pin<KBox<Self >>>> )?; >>>> >>>> let this = KBox::pin_init( >>>> - try_pin_init!(Self { >>>> + try_pin_init!(&this in Self { >>>> gpu <- Gpu::new(pdev, bar)?, >>>> + gsp <- { >>>> + // SAFETY: `this.gpu` is initialized to a valid value. >>>> + let gpu = unsafe { &(*this.as_ptr()).gpu }; >>>> + >>>> + gpu.start_gsp(pdev)? >>>> + }, >>> >>> Please use pin_chain() [1] for this. >> >> Sorry, but I couldn't figure out how I can use pin_chain here (and >> couldn't find any relevant example in the kernel code either). Can you >> elaborate a bit? > > I thought of just doing the following, which I think should be equivalent (diff > against current nova-next). > > diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs > index 274989ea1fb4..6d62867f7503 100644 > --- a/drivers/gpu/nova-core/driver.rs > +++ b/drivers/gpu/nova-core/driver.rs > @@ -41,7 +41,9 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> Result<Pin<KBox<Self > > let this = KBox::pin_init( > try_pin_init!(Self { > - gpu <- Gpu::new(pdev, bar)?, > + gpu <- Gpu::new(pdev, bar)?.pin_chain(|gpu| { > + gpu.start_gsp(pdev) > + }), > _reg: auxiliary::Registration::new( > pdev.as_ref(), > c_str!("nova-drm"), > diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs > index 8caecaf7dfb4..211bc1a5a5b3 100644 > --- a/drivers/gpu/nova-core/gpu.rs > +++ b/drivers/gpu/nova-core/gpu.rs > @@ -266,7 +266,7 @@ fn run_fwsec_frts( > pub(crate) fn new( > pdev: &pci::Device<device::Bound>, > devres_bar: Arc<Devres<Bar0>>, > - ) -> Result<impl PinInit<Self>> { > + ) -> Result<impl PinInit<Self, Error>> { > let bar = devres_bar.access(pdev.as_ref())?; > let spec = Spec::new(bar)?; > let fw = Firmware::new(pdev.as_ref(), spec.chipset, FIRMWARE_VERSION)?; > @@ -302,11 +302,16 @@ pub(crate) fn new( > > Self::run_fwsec_frts(pdev.as_ref(), &gsp_falcon, bar, &bios, &fb_layout)?; > > - Ok(pin_init!(Self { > + Ok(try_pin_init!(Self { > spec, > bar: devres_bar, > fw, > sysmem_flush, > })) > } > + > + pub(crate) fn start_gsp(&self, _pdev: &pci::Device<device::Core>) -> Result { > + // noop > + Ok(()) > + } > } > > But maybe it doesn't capture your intend?The issue is that `start_gsp` returns a value (currently a placeholder `()`, but it will change into a real type) that needs to be stored into the newly-introduced `gsp` member of `NovaCore`. I could not figure how how `pin_chain` could help with this (and this is the same problem for the other `unsafe` statements in `firmware/gsp.rs`). It is a common pattern when initializing a pinned object, so I agree it would be nice support this without unsafe code.
Danilo Krummrich
2025-Sep-03 11:05 UTC
[PATCH v3 02/11] gpu: nova-core: move GSP boot code out of `Gpu` constructor
On Wed Sep 3, 2025 at 12:44 PM CEST, Alexandre Courbot wrote:> On Wed Sep 3, 2025 at 5:26 PM JST, Danilo Krummrich wrote: >> On Wed Sep 3, 2025 at 9:08 AM CEST, Alexandre Courbot wrote: >>> On Wed Sep 3, 2025 at 4:53 AM JST, Danilo Krummrich wrote: >>>> On Tue Sep 2, 2025 at 4:31 PM CEST, Alexandre Courbot wrote: >>>>> diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs >>>>> index 274989ea1fb4a5e3e6678a08920ddc76d2809ab2..1062014c0a488e959379f009c2e8029ffaa1e2f8 100644 >>>>> --- a/drivers/gpu/nova-core/driver.rs >>>>> +++ b/drivers/gpu/nova-core/driver.rs >>>>> @@ -6,6 +6,8 @@ >>>>> >>>>> #[pin_data] >>>>> pub(crate) struct NovaCore { >>>>> + // Placeholder for the real `Gsp` object once it is built. >>>>> + pub(crate) gsp: (), >>>>> #[pin] >>>>> pub(crate) gpu: Gpu, >>>>> _reg: auxiliary::Registration, >>>>> @@ -40,8 +42,14 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> Result<Pin<KBox<Self >>>>> )?; >>>>> >>>>> let this = KBox::pin_init( >>>>> - try_pin_init!(Self { >>>>> + try_pin_init!(&this in Self { >>>>> gpu <- Gpu::new(pdev, bar)?, >>>>> + gsp <- { >>>>> + // SAFETY: `this.gpu` is initialized to a valid value. >>>>> + let gpu = unsafe { &(*this.as_ptr()).gpu }; >>>>> + >>>>> + gpu.start_gsp(pdev)? >>>>> + }, >>>> >>>> Please use pin_chain() [1] for this. >>> >>> Sorry, but I couldn't figure out how I can use pin_chain here (and >>> couldn't find any relevant example in the kernel code either). Can you >>> elaborate a bit? >> >> I thought of just doing the following, which I think should be equivalent (diff >> against current nova-next). >> >> diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs >> index 274989ea1fb4..6d62867f7503 100644 >> --- a/drivers/gpu/nova-core/driver.rs >> +++ b/drivers/gpu/nova-core/driver.rs >> @@ -41,7 +41,9 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> Result<Pin<KBox<Self >> >> let this = KBox::pin_init( >> try_pin_init!(Self { >> - gpu <- Gpu::new(pdev, bar)?, >> + gpu <- Gpu::new(pdev, bar)?.pin_chain(|gpu| { >> + gpu.start_gsp(pdev) >> + }), >> _reg: auxiliary::Registration::new( >> pdev.as_ref(), >> c_str!("nova-drm"), >> diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs >> index 8caecaf7dfb4..211bc1a5a5b3 100644 >> --- a/drivers/gpu/nova-core/gpu.rs >> +++ b/drivers/gpu/nova-core/gpu.rs >> @@ -266,7 +266,7 @@ fn run_fwsec_frts( >> pub(crate) fn new( >> pdev: &pci::Device<device::Bound>, >> devres_bar: Arc<Devres<Bar0>>, >> - ) -> Result<impl PinInit<Self>> { >> + ) -> Result<impl PinInit<Self, Error>> { >> let bar = devres_bar.access(pdev.as_ref())?; >> let spec = Spec::new(bar)?; >> let fw = Firmware::new(pdev.as_ref(), spec.chipset, FIRMWARE_VERSION)?; >> @@ -302,11 +302,16 @@ pub(crate) fn new( >> >> Self::run_fwsec_frts(pdev.as_ref(), &gsp_falcon, bar, &bios, &fb_layout)?; >> >> - Ok(pin_init!(Self { >> + Ok(try_pin_init!(Self { >> spec, >> bar: devres_bar, >> fw, >> sysmem_flush, >> })) >> } >> + >> + pub(crate) fn start_gsp(&self, _pdev: &pci::Device<device::Core>) -> Result { >> + // noop >> + Ok(()) >> + } >> } >> >> But maybe it doesn't capture your intend? > > The issue is that `start_gsp` returns a value (currently a placeholder > `()`, but it will change into a real type) that needs to be stored into > the newly-introduced `gsp` member of `NovaCore`. I could not figure how > how `pin_chain` could help with this (and this is the same problem for > the other `unsafe` statements in `firmware/gsp.rs`).Ok, I see, I think Benno is already working on a solution to access previously initialized fields from subsequent initializers. @Benno: What's the status of this? I haven't seen an issue for that in the pin-init GitHub repo, should we create one? However, in this case I'm a bit confused why we want Gsp next to Gpu? Why not just make Gsp a member of Gpu then? I thought the intent was to keep temporary values local to start_gsp() and not store them next to Gpu in the same allocation?> It is a common pattern when initializing a pinned object, so I agree it > would be nice support this without unsafe code.