[PATCH] drm/i915/gvt: Use KVM r/w to access guest opregion

Zhang, Tina tina.zhang at intel.com
Fri Jan 26 06:53:44 UTC 2018



> -----Original Message-----
> From: Wang, Zhenyu Z
> Sent: Friday, January 26, 2018 2:29 PM
> To: Zhang, Tina <tina.zhang at intel.com>
> Cc: intel-gvt-dev at lists.freedesktop.org; Zhao, Yan Y <yan.y.zhao at intel.com>;
> Zhang, Xiong Y <xiong.y.zhang at intel.com>
> Subject: Re: [PATCH] drm/i915/gvt: Use KVM r/w to access guest opregion
> 
> On 2018.01.26 00:03:03 +0000, Zhang, Tina wrote:
> > > On 2018.01.25 16:40:21 +0800, Tina Zhang wrote:
> > > > For KVMGT, the guest opregion, which is handled by VFIO, is
> > > > actually a piece of guest memory which won't be accessed by
> > > > devices. So, its mfn shouldn't be obtained through VFIO interface.
> > > > This patch uses KVM r/w interface to access the data in guest opregion.
> > > >
> > >
> > > gvt uses virtualized opregion for vgpu, why not just r/w vgpu opregion?
> > As the comments said in "kvmgt.c":
> >
> > static int kvmgt_set_opregion(void *p_vgpu) {
> >         struct intel_vgpu *vgpu = (struct intel_vgpu *)p_vgpu;
> >         void *base;
> >         int ret;
> >
> >         /* Each vgpu has its own opregion, although VFIO would create another
> >          * one later. This one is used to expose opregion to VFIO. And the
> >          * other one created by VFIO later, is used by guest actually.
> >          */
> >         base = vgpu_opregion(vgpu)->va;
> >         if (!base)
> >                 return -ENOMEM;
> >
> > Here "This one" means the vgpu opregion created and populated by device
> model.
> > "the other one" is actually used by guest VM.
> >
> 
> yeah, forgot that one has already been setup, comment below.
> 
> 
> > > > Fix the guest opregion accessing issue when host "intel_iommu=on".
> > > >
> > > > Signed-off-by: Tina Zhang <tina.zhang at intel.com>
> > > > Cc: Yan Zhao <yan.y.zhao at intel.com>
> > > > Cc: Xiong Zhang <xiong.y.zhang at intel.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/gvt/gvt.h      |  1 -
> > > >  drivers/gpu/drm/i915/gvt/opregion.c | 95
> > > > ++++++++++++++++++++++++++-----------
> > > >  2 files changed, 68 insertions(+), 28 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/gvt/gvt.h
> > > > b/drivers/gpu/drm/i915/gvt/gvt.h index 7dc7a80..205d88d 100644
> > > > --- a/drivers/gpu/drm/i915/gvt/gvt.h
> > > > +++ b/drivers/gpu/drm/i915/gvt/gvt.h
> > > > @@ -127,7 +127,6 @@ struct intel_vgpu_irq {  struct
> > > > intel_vgpu_opregion {
> > > >  	bool mapped;
> > > >  	void *va;
> > > > -	void *va_gopregion;
> > > >  	u32 gfn[INTEL_GVT_OPREGION_PAGES];  };
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/gvt/opregion.c
> > > > b/drivers/gpu/drm/i915/gvt/opregion.c
> > > > index 8420d1f..4030233 100644
> > > > --- a/drivers/gpu/drm/i915/gvt/opregion.c
> > > > +++ b/drivers/gpu/drm/i915/gvt/opregion.c
> > > > @@ -299,20 +299,13 @@ int
> > > > intel_vgpu_opregion_base_write_handler(struct intel_vgpu *vgpu,
> > > > u32
> > > > gpa)  {
> > > >
> > > >  	int i, ret = 0;
> > > > -	unsigned long pfn;
> > > >
> > > >  	gvt_dbg_core("emulate opregion from kernel\n");
> > > >
> > > >  	switch (intel_gvt_host.hypervisor_type) {
> > > >  	case INTEL_GVT_HYPERVISOR_KVM:
> > > > -		pfn = intel_gvt_hypervisor_gfn_to_mfn(vgpu, gpa >>
> > > PAGE_SHIFT);
> > > > -		vgpu_opregion(vgpu)->va_gopregion = memremap(pfn <<
> > > PAGE_SHIFT,
> > > > -						INTEL_GVT_OPREGION_SIZE,
> > > > -						MEMREMAP_WB);
> > > > -		if (!vgpu_opregion(vgpu)->va_gopregion) {
> > > > -			gvt_vgpu_err("failed to map guest opregion\n");
> > > > -			ret = -EFAULT;
> > > > -		}
> > > > +		for (i = 0; i < INTEL_GVT_OPREGION_PAGES; i++)
> > > > +			vgpu_opregion(vgpu)->gfn[i] = (gpa >> PAGE_SHIFT) +
> > > i;
> > > >  		vgpu_opregion(vgpu)->mapped = true;
> > > >  		break;
> > > >  	case INTEL_GVT_HYPERVISOR_XEN:
> > > > @@ -352,10 +345,7 @@ void intel_vgpu_clean_opregion(struct
> > > > intel_vgpu
> > > *vgpu)
> > > >  		if (vgpu_opregion(vgpu)->mapped)
> > > >  			map_vgpu_opregion(vgpu, false);
> > > >  	} else if (intel_gvt_host.hypervisor_type ==
> > > INTEL_GVT_HYPERVISOR_KVM) {
> > > > -		if (vgpu_opregion(vgpu)->mapped) {
> > > > -			memunmap(vgpu_opregion(vgpu)->va_gopregion);
> > > > -			vgpu_opregion(vgpu)->va_gopregion = NULL;
> > > > -		}
> > > > +		/* Guest opregion is released by VFIO */
> > > >  	}
> > > >  	free_pages((unsigned long)vgpu_opregion(vgpu)->va,
> > > >  		   get_order(INTEL_GVT_OPREGION_SIZE));
> > > > @@ -480,19 +470,38 @@ static bool querying_capabilities(u32 scic)
> > > >   */
> > > >  int intel_vgpu_emulate_opregion_request(struct intel_vgpu *vgpu,
> > > > u32
> > > > swsci)  {
> > > > -	u32 *scic, *parm;
> > > > +	u32 scic, parm;
> > > >  	u32 func, subfunc;
> > > > +	u64 scic_pa = 0, parm_pa = 0;
> > > > +	int ret;
> > > >
> > > >  	switch (intel_gvt_host.hypervisor_type) {
> > > >  	case INTEL_GVT_HYPERVISOR_XEN:
> > > > -		scic = vgpu_opregion(vgpu)->va +
> > > INTEL_GVT_OPREGION_SCIC;
> > > > -		parm = vgpu_opregion(vgpu)->va +
> > > INTEL_GVT_OPREGION_PARM;
> > > > +		scic = *((u32 *)vgpu_opregion(vgpu)->va +
> > > > +					INTEL_GVT_OPREGION_SCIC);
> > > > +		parm = *((u32 *)vgpu_opregion(vgpu)->va +
> > > > +					INTEL_GVT_OPREGION_PARM);
> > > >  		break;
> > > >  	case INTEL_GVT_HYPERVISOR_KVM:
> > > > -		scic = vgpu_opregion(vgpu)->va_gopregion +
> > > > -						INTEL_GVT_OPREGION_SCIC;
> > > > -		parm = vgpu_opregion(vgpu)->va_gopregion +
> > > > -
> > > 	INTEL_GVT_OPREGION_PARM;
> > > > +		scic_pa = vgpu_opregion(vgpu)->gfn[0] +
> > > INTEL_GVT_OPREGION_SCIC;
> > > > +		parm_pa = vgpu_opregion(vgpu)->gfn[0] +
> > > INTEL_GVT_OPREGION_PARM;
> 
> Looks mis use of gfn for gpa here?
Indeed.

Tina
> 
> > > > +
> > > > +		ret = intel_gvt_hypervisor_read_gpa(vgpu, scic_pa,
> > > > +						    &scic, sizeof(scic));
> > > > +		if (ret) {
> > > > +			gvt_vgpu_err("guet opregion read error %d, gpa
> > > 0x%llx, len %lu\n",
> > > > +				ret, scic_pa, sizeof(scic));
> > > > +			return ret;
> > > > +		}
> > > > +
> > > > +		ret = intel_gvt_hypervisor_read_gpa(vgpu, parm_pa,
> > > > +						    &parm, sizeof(parm));
> > > > +		if (ret) {
> > > > +			gvt_vgpu_err("guet opregion read error %d, gpa
> > > 0x%llx, len %lu\n",
> > > > +				ret, scic_pa, sizeof(scic));
> > > > +			return ret;
> > > > +		}
> > > > +
> > > >  		break;
> > > >  	default:
> > > >  		gvt_vgpu_err("not supported hypervisor\n"); @@ -510,9
> > > +519,9 @@ int
> > > > intel_vgpu_emulate_opregion_request(struct intel_vgpu *vgpu, u32 swsci)
> > > >  		return 0;
> > > >  	}
> > > >
> > > > -	func = GVT_OPREGION_FUNC(*scic);
> > > > -	subfunc = GVT_OPREGION_SUBFUNC(*scic);
> > > > -	if (!querying_capabilities(*scic)) {
> > > > +	func = GVT_OPREGION_FUNC(scic);
> > > > +	subfunc = GVT_OPREGION_SUBFUNC(scic);
> > > > +	if (!querying_capabilities(scic)) {
> > > >  		gvt_vgpu_err("requesting runtime service: func \"%s\","
> > > >  				" subfunc \"%s\"\n",
> > > >  				opregion_func_name(func),
> > > > @@ -521,11 +530,43 @@ int
> > > > intel_vgpu_emulate_opregion_request(struct
> > > intel_vgpu *vgpu, u32 swsci)
> > > >  		 * emulate exit status of function call, '0' means
> > > >  		 * "failure, generic, unsupported or unknown cause"
> > > >  		 */
> > > > -		*scic &= ~OPREGION_SCIC_EXIT_MASK;
> > > > -		return 0;
> > > > +		scic &= ~OPREGION_SCIC_EXIT_MASK;
> > > > +		goto out;
> > > > +	}
> > > > +
> > > > +	scic = 0;
> > > > +	parm = 0;
> > > > +
> > > > +out:
> > > > +	switch (intel_gvt_host.hypervisor_type) {
> > > > +	case INTEL_GVT_HYPERVISOR_XEN:
> > > > +		*((u32 *)vgpu_opregion(vgpu)->va +
> > > > +					INTEL_GVT_OPREGION_SCIC) = scic;
> > > > +		*((u32 *)vgpu_opregion(vgpu)->va +
> > > > +					INTEL_GVT_OPREGION_PARM) =
> > > parm;
> > > > +		break;
> > > > +	case INTEL_GVT_HYPERVISOR_KVM:
> > > > +		ret = intel_gvt_hypervisor_write_gpa(vgpu, scic_pa,
> > > > +						    &scic, sizeof(scic));
> > > > +		if (ret) {
> > > > +			gvt_vgpu_err("guet opregion write error %d, gpa
> > > 0x%llx, len %lu\n",
> > > > +				ret, scic_pa, sizeof(scic));
> > > > +			return ret;
> > > > +		}
> > > > +
> > > > +		ret = intel_gvt_hypervisor_write_gpa(vgpu, parm_pa,
> > > > +						    &parm, sizeof(parm));
> > > > +		if (ret) {
> > > > +			gvt_vgpu_err("guet opregion write error %d, gpa
> > > 0x%llx, len %lu\n",
> > > > +				ret, scic_pa, sizeof(scic));
> > > > +			return ret;
> > > > +		}
> > > > +
> > > > +		break;
> > > > +	default:
> > > > +		gvt_vgpu_err("not supported hypervisor\n");
> > > > +		return -EINVAL;
> > > >  	}
> > > >
> > > > -	*scic = 0;
> > > > -	*parm = 0;
> > > >  	return 0;
> > > >  }
> > > > --
> > > > 2.7.4
> > > >
> > >
> > > --
> > > Open Source Technology Center, Intel ltd.
> > >
> > > $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827
> 
> --
> Open Source Technology Center, Intel ltd.
> 
> $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827


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