Re: [RFC 02/10] drm/i915/gvt: get ready of memory for pvmmio

[Zhenyu Wang <zhenyuw@linux.intel.com>]

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On 2018.09.27 12:37:47 -0400, Xiaolin Zhang wrote:
> To enable pvmmio feature, we need to prepare one 4K shared page
> which will be accessed by both guest and backend i915 driver.
> 
> guest i915 allocate one page memory and then the guest physical address is
> passed to backend i915 driver through PVINFO register so that backend i915
> driver can access this shared page without hypeviser trap cost for shared
> data exchagne via hyperviser read_gpa functionality.
> 
> Signed-off-by: Xiaolin Zhang <xiaolin.zhang@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c    |  5 +++++
>  drivers/gpu/drm/i915/i915_drv.h    |  3 +++
>  drivers/gpu/drm/i915/i915_pvinfo.h | 25 ++++++++++++++++++++++++-
>  drivers/gpu/drm/i915/i915_vgpu.c   | 17 +++++++++++++++++
>  4 files changed, 49 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index ade9bca..815a4dd 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -885,6 +885,7 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv)
>  		return -ENODEV;
>  
>  	spin_lock_init(&dev_priv->irq_lock);
> +	spin_lock_init(&dev_priv->shared_page_lock);
>  	spin_lock_init(&dev_priv->gpu_error.lock);
>  	mutex_init(&dev_priv->backlight_lock);
>  	spin_lock_init(&dev_priv->uncore.lock);
> @@ -987,6 +988,8 @@ static void i915_mmio_cleanup(struct drm_i915_private *dev_priv)
>  
>  	intel_teardown_mchbar(dev_priv);
>  	pci_iounmap(pdev, dev_priv->regs);
> +	if (intel_vgpu_active(dev_priv) && dev_priv->shared_page)
> +		free_pages((unsigned long)dev_priv->shared_page, 0);
>  }
>  
>  /**
> @@ -1029,6 +1032,8 @@ static int i915_driver_init_mmio(struct drm_i915_private *dev_priv)
>  	return 0;
>  
>  err_uncore:
> +	if (intel_vgpu_active(dev_priv) && dev_priv->shared_page)
> +		free_pages((unsigned long)dev_priv->shared_page, 0);
>  	intel_uncore_fini(dev_priv);
>  err_bridge:
>  	pci_dev_put(dev_priv->bridge_dev);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 174d618..76d7e9c 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -56,6 +56,7 @@
>  
>  #include "i915_params.h"
>  #include "i915_reg.h"
> +#include "i915_pvinfo.h"
>  #include "i915_utils.h"
>  
>  #include "intel_bios.h"
> @@ -1623,6 +1624,8 @@ struct drm_i915_private {
>  	resource_size_t stolen_usable_size;	/* Total size minus reserved ranges */
>  
>  	void __iomem *regs;
> +	struct gvt_shared_page *shared_page;
> +	spinlock_t shared_page_lock;
>  
>  	struct intel_uncore uncore;
>  
> diff --git a/drivers/gpu/drm/i915/i915_pvinfo.h b/drivers/gpu/drm/i915/i915_pvinfo.h
> index 697e998..ab839a7 100644
> --- a/drivers/gpu/drm/i915/i915_pvinfo.h
> +++ b/drivers/gpu/drm/i915/i915_pvinfo.h
> @@ -49,6 +49,25 @@ enum vgt_g2v_type {
>  	VGT_G2V_MAX,
>  };
>  
> +struct pv_ppgtt_update {
> +	u64 pdp;
> +	u64 start;
> +	u64 length;
> +	u32 cache_level;
> +};
> +
> +/*
> + * shared page(4KB) between gvt and VM, could be allocated by guest driver
> + * or a fixed location in PCI bar 0 region
> + */
> +struct gvt_shared_page {
> +	u32 elsp_data[4];
> +	u32 reg_addr;
> +	u32 disable_irq;
> +	struct pv_ppgtt_update pv_ppgtt;
> +	u32 rsvd2[0x400 - 13];
> +};

Could we define offset for shared page fields instead of a struct?
Which is wasting space I think.

> +
>  #define VGPU_PVMMIO(vgpu) vgpu_vreg_t(vgpu, vgtif_reg(enable_pvmmio))
>  
>  /*
> @@ -120,8 +139,12 @@ struct vgt_if {
>  	u32 execlist_context_descriptor_lo;
>  	u32 execlist_context_descriptor_hi;
>  	u32 enable_pvmmio;
> +	struct {
> +		u32 lo;
> +		u32 hi;
> +	} shared_page_gpa;
>  
> -	u32  rsv7[0x200 - 25];    /* pad to one page */
> +	u32  rsv7[0x200 - 27];    /* pad to one page */
>  } __packed;
>  
>  #define vgtif_reg(x) \
> diff --git a/drivers/gpu/drm/i915/i915_vgpu.c b/drivers/gpu/drm/i915/i915_vgpu.c
> index d22c5ca..10ae94b 100644
> --- a/drivers/gpu/drm/i915/i915_vgpu.c
> +++ b/drivers/gpu/drm/i915/i915_vgpu.c
> @@ -62,6 +62,7 @@ void i915_check_vgpu(struct drm_i915_private *dev_priv)
>  {
>  	u64 magic;
>  	u16 version_major;
> +	u64 shared_page_gpa;
>  
>  	BUILD_BUG_ON(sizeof(struct vgt_if) != VGT_PVINFO_SIZE);
>  
> @@ -89,6 +90,22 @@ void i915_check_vgpu(struct drm_i915_private *dev_priv)
>  	dev_priv->vgpu.active = true;
>  	DRM_INFO("Virtual GPU for Intel GVT-g detected with pvmmio 0x%x\n",
>  		i915_modparams.enable_pvmmio);
> +
> +	if (intel_vgpu_active(dev_priv) && i915_modparams.enable_pvmmio) {
> +		dev_priv->shared_page =  (struct gvt_shared_page *)
> +				__get_free_pages(GFP_KERNEL | __GFP_ZERO, 0);
> +		if (!dev_priv->shared_page) {
> +			DRM_ERROR("out of memory for shared page memory\n");
> +			return;
> +		}
> +		shared_page_gpa = __pa(dev_priv->shared_page);
> +		__raw_i915_write32(dev_priv, vgtif_reg(shared_page_gpa.lo),
> +				lower_32_bits(shared_page_gpa));
> +		__raw_i915_write32(dev_priv, vgtif_reg(shared_page_gpa.hi),
> +				upper_32_bits(shared_page_gpa));
> +		DRM_INFO("VGPU shared page enabled\n");
> +	}
> +
>  }
>  
>  bool intel_vgpu_has_full_48bit_ppgtt(struct drm_i915_private *dev_priv)
> -- 
> 1.8.3.1
> 

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