Re: [PATCH v9 05/11] arm/arm64: vgic: Introduce VENG0 and VENG1 fields to vmcr struct

[Christoffer Dall <christoffer.dall@linaro.org>]

On Thu, Dec 08, 2016 at 12:52:39PM +0100, Auger Eric wrote:
> Hi Vijay,
> 
> On 28/11/2016 15:28, Christoffer Dall wrote:
> > On Wed, Nov 23, 2016 at 06:31:52PM +0530, vijay.kilari@gmail.com wrote:
> >> From: Vijaya Kumar K <Vijaya.Kumar@cavium.com>
> >>
> >> ICC_VMCR_EL2 supports virtual access to ICC_IGRPEN1_EL1.Enable
> >> and ICC_IGRPEN0_EL1.Enable fields. Add grpen0 and grpen1 member
> >> variables to struct vmcr to support read and write of these fields.
> >>
> >> Also refactor vgic_set_vmcr and vgic_get_vmcr() code.
> >> Drop ICH_VMCR_CTLR_SHIFT and ICH_VMCR_CTLR_MASK macros and instead
> >> use ICH_VMCR_EOI* and ICH_VMCR_CBPR* macros
> >> .
> >> Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@cavium.com>
> >> ---
> >>  include/linux/irqchip/arm-gic-v3.h |  2 --
> >>  virt/kvm/arm/vgic/vgic-mmio-v2.c   | 16 ----------------
> >>  virt/kvm/arm/vgic/vgic-mmio.c      | 16 ++++++++++++++++
> >>  virt/kvm/arm/vgic/vgic-v3.c        | 22 ++++++++++++++++++++--
> >>  virt/kvm/arm/vgic/vgic.h           |  5 +++++
> >>  5 files changed, 41 insertions(+), 20 deletions(-)
> >>
> >> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> >> index b4f8287..406fc3e 100644
> >> --- a/include/linux/irqchip/arm-gic-v3.h
> >> +++ b/include/linux/irqchip/arm-gic-v3.h
> >> @@ -404,8 +404,6 @@
> >>  #define ICH_HCR_EN			(1 << 0)
> >>  #define ICH_HCR_UIE			(1 << 1)
> >>  
> >> -#define ICH_VMCR_CTLR_SHIFT		0
> >> -#define ICH_VMCR_CTLR_MASK		(0x21f << ICH_VMCR_CTLR_SHIFT)
> >>  #define ICH_VMCR_CBPR_SHIFT		4
> >>  #define ICH_VMCR_CBPR_MASK		(1 << ICH_VMCR_CBPR_SHIFT)
> >>  #define ICH_VMCR_EOIM_SHIFT		9
> >> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >> index 2cb04b7..ad353b5 100644
> >> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >> @@ -212,22 +212,6 @@ static void vgic_mmio_write_sgipends(struct kvm_vcpu *vcpu,
> >>  	}
> >>  }
> >>  
> >> -static void vgic_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
> >> -{
> >> -	if (kvm_vgic_global_state.type == VGIC_V2)
> >> -		vgic_v2_set_vmcr(vcpu, vmcr);
> >> -	else
> >> -		vgic_v3_set_vmcr(vcpu, vmcr);
> >> -}
> >> -
> >> -static void vgic_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
> >> -{
> >> -	if (kvm_vgic_global_state.type == VGIC_V2)
> >> -		vgic_v2_get_vmcr(vcpu, vmcr);
> >> -	else
> >> -		vgic_v3_get_vmcr(vcpu, vmcr);
> >> -}
> >> -
> >>  #define GICC_ARCH_VERSION_V2	0x2
> >>  
> >>  /* These are for userland accesses only, there is no guest-facing emulation. */
> >> diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
> >> index 0d1bc98..f81e0e5 100644
> >> --- a/virt/kvm/arm/vgic/vgic-mmio.c
> >> +++ b/virt/kvm/arm/vgic/vgic-mmio.c
> >> @@ -416,6 +416,22 @@ int vgic_validate_mmio_region_addr(struct kvm_device *dev,
> >>  	return -ENXIO;
> >>  }
> >>  
> >> +void vgic_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
> >> +{
> >> +	if (kvm_vgic_global_state.type == VGIC_V2)
> >> +		vgic_v2_set_vmcr(vcpu, vmcr);
> >> +	else
> >> +		vgic_v3_set_vmcr(vcpu, vmcr);
> >> +}
> >> +
> >> +void vgic_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
> >> +{
> >> +	if (kvm_vgic_global_state.type == VGIC_V2)
> >> +		vgic_v2_get_vmcr(vcpu, vmcr);
> >> +	else
> >> +		vgic_v3_get_vmcr(vcpu, vmcr);
> >> +}
> >> +
> >>  /*
> >>   * kvm_mmio_read_buf() returns a value in a format where it can be converted
> >>   * to a byte array and be directly observed as the guest wanted it to appear
> >> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> >> index 9f0dae3..a3ff04b 100644
> >> --- a/virt/kvm/arm/vgic/vgic-v3.c
> >> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> >> @@ -175,10 +175,19 @@ void vgic_v3_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
> >>  {
> >>  	u32 vmcr;
> >>  
> >> -	vmcr  = (vmcrp->ctlr << ICH_VMCR_CTLR_SHIFT) & ICH_VMCR_CTLR_MASK;
> >> +	/*
> >> +	 * Ignore the FIQen bit, because GIC emulation always implies
> >> +	 * SRE=1 which means the vFIQEn bit is also RES1.
> >> +	 */
> >> +	vmcr = (vmcrp->ctlr & ICC_CTLR_EL1_EOImode_MASK) >>
> >> +		ICC_CTLR_EL1_EOImode_SHIFT;
> >> +	vmcr = (vmcr << ICH_VMCR_EOIM_SHIFT) & ICH_VMCR_EOIM_MASK;

> I am not able to understand why we use ICC_CTLR _*macros here? Please
> could you explain it to me? Besides if we want to ignore the FIQen bit
> can't we change the ICH_VMCR_CTLR_MASK value?
> 
This first statement is setting the vmcr to the ctlr's bit[1], but
placed in bit[0], and then the next statement is moving that bit value
to the corresponding place in the vmcr.  I think this is correct
(although a little opaque).

There's also a newer series on the list, just so you know.

Thanks,
-Christoffer