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Commit 6d52f35a authored by Andre Przywara's avatar Andre Przywara Committed by Christoffer Dall
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arm64: KVM: add SGI generation register emulation 



While the generation of a (virtual) inter-processor interrupt (SGI)
on a GICv2 works by writing to a MMIO register, GICv3 uses the system
register ICC_SGI1R_EL1 to trigger them.
Add a trap handler function that calls the new SGI register handler
in the GICv3 code. As ICC_SRE_EL1.SRE at this point is still always 0,
this will not trap yet, but will only be used later when all the data
structures have been initialized properly.

Signed-off-by: default avatarAndre Przywara <andre.przywara@arm.com>
Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
parent 7e580278

arch/arm64/kvm/sys_regs.c

+27 −0
Original line number Diff line number Diff line
@@ -165,6 +165,27 @@ static bool access_sctlr(struct kvm_vcpu *vcpu, 
	return true;

}



/*

 * Trap handler for the GICv3 SGI generation system register.

 * Forward the request to the VGIC emulation.

 * The cp15_64 code makes sure this automatically works

 * for both AArch64 and AArch32 accesses.

 */

static bool access_gic_sgi(struct kvm_vcpu *vcpu,

			   const struct sys_reg_params *p,

			   const struct sys_reg_desc *r)

{

	u64 val;



	if (!p->is_write)

		return read_from_write_only(vcpu, p);



	val = *vcpu_reg(vcpu, p->Rt);

	vgic_v3_dispatch_sgi(vcpu, val);



	return true;

}



static bool trap_raz_wi(struct kvm_vcpu *vcpu,

			const struct sys_reg_params *p,

			const struct sys_reg_desc *r)
@@ -434,6 +455,9 @@ static const struct sys_reg_desc sys_reg_descs[] = { 
	{ Op0(0b11), Op1(0b000), CRn(0b1100), CRm(0b0000), Op2(0b000),

	  NULL, reset_val, VBAR_EL1, 0 },



	/* ICC_SGI1R_EL1 */

	{ Op0(0b11), Op1(0b000), CRn(0b1100), CRm(0b1011), Op2(0b101),

	  access_gic_sgi },

	/* ICC_SRE_EL1 */

	{ Op0(0b11), Op1(0b000), CRn(0b1100), CRm(0b1100), Op2(0b101),

	  trap_raz_wi },
@@ -666,6 +690,8 @@ static const struct sys_reg_desc cp14_64_regs[] = { 
 * register).

 */

static const struct sys_reg_desc cp15_regs[] = {

	{ Op1( 0), CRn( 0), CRm(12), Op2( 0), access_gic_sgi },



	{ Op1( 0), CRn( 1), CRm( 0), Op2( 0), access_sctlr, NULL, c1_SCTLR },

	{ Op1( 0), CRn( 2), CRm( 0), Op2( 0), access_vm_reg, NULL, c2_TTBR0 },

	{ Op1( 0), CRn( 2), CRm( 0), Op2( 1), access_vm_reg, NULL, c2_TTBR1 },
@@ -713,6 +739,7 @@ static const struct sys_reg_desc cp15_regs[] = { 


static const struct sys_reg_desc cp15_64_regs[] = {

	{ Op1( 0), CRn( 0), CRm( 2), Op2( 0), access_vm_reg, NULL, c2_TTBR0 },

	{ Op1( 0), CRn( 0), CRm(12), Op2( 0), access_gic_sgi },

	{ Op1( 1), CRn( 0), CRm( 2), Op2( 0), access_vm_reg, NULL, c2_TTBR1 },

};

include/kvm/arm_vgic.h

+1 −0
Original line number Diff line number Diff line
@@ -307,6 +307,7 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu); 
void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu);

int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num,

			bool level);

void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg);

int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);

bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,

		      struct kvm_exit_mmio *mmio);

virt/kvm/arm/vgic-v3-emul.c

+111 −0
Original line number Diff line number Diff line
@@ -841,6 +841,117 @@ void vgic_v3_init_emulation(struct kvm *kvm) 
	kvm->arch.max_vcpus = KVM_MAX_VCPUS;

}



/*

 * Compare a given affinity (level 1-3 and a level 0 mask, from the SGI

 * generation register ICC_SGI1R_EL1) with a given VCPU.

 * If the VCPU's MPIDR matches, return the level0 affinity, otherwise

 * return -1.

 */

static int match_mpidr(u64 sgi_aff, u16 sgi_cpu_mask, struct kvm_vcpu *vcpu)

{

	unsigned long affinity;

	int level0;



	/*

	 * Split the current VCPU's MPIDR into affinity level 0 and the

	 * rest as this is what we have to compare against.

	 */

	affinity = kvm_vcpu_get_mpidr_aff(vcpu);

	level0 = MPIDR_AFFINITY_LEVEL(affinity, 0);

	affinity &= ~MPIDR_LEVEL_MASK;



	/* bail out if the upper three levels don't match */

	if (sgi_aff != affinity)

		return -1;



	/* Is this VCPU's bit set in the mask ? */

	if (!(sgi_cpu_mask & BIT(level0)))

		return -1;



	return level0;

}



#define SGI_AFFINITY_LEVEL(reg, level) \

	((((reg) & ICC_SGI1R_AFFINITY_## level ##_MASK) \

	>> ICC_SGI1R_AFFINITY_## level ##_SHIFT) << MPIDR_LEVEL_SHIFT(level))



/**

 * vgic_v3_dispatch_sgi - handle SGI requests from VCPUs

 * @vcpu: The VCPU requesting a SGI

 * @reg: The value written into the ICC_SGI1R_EL1 register by that VCPU

 *

 * With GICv3 (and ARE=1) CPUs trigger SGIs by writing to a system register.

 * This will trap in sys_regs.c and call this function.

 * This ICC_SGI1R_EL1 register contains the upper three affinity levels of the

 * target processors as well as a bitmask of 16 Aff0 CPUs.

 * If the interrupt routing mode bit is not set, we iterate over all VCPUs to

 * check for matching ones. If this bit is set, we signal all, but not the

 * calling VCPU.

 */

void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg)

{

	struct kvm *kvm = vcpu->kvm;

	struct kvm_vcpu *c_vcpu;

	struct vgic_dist *dist = &kvm->arch.vgic;

	u16 target_cpus;

	u64 mpidr;

	int sgi, c;

	int vcpu_id = vcpu->vcpu_id;

	bool broadcast;

	int updated = 0;



	sgi = (reg & ICC_SGI1R_SGI_ID_MASK) >> ICC_SGI1R_SGI_ID_SHIFT;

	broadcast = reg & BIT(ICC_SGI1R_IRQ_ROUTING_MODE_BIT);

	target_cpus = (reg & ICC_SGI1R_TARGET_LIST_MASK) >> ICC_SGI1R_TARGET_LIST_SHIFT;

	mpidr = SGI_AFFINITY_LEVEL(reg, 3);

	mpidr |= SGI_AFFINITY_LEVEL(reg, 2);

	mpidr |= SGI_AFFINITY_LEVEL(reg, 1);



	/*

	 * We take the dist lock here, because we come from the sysregs

	 * code path and not from the MMIO one (which already takes the lock).

	 */

	spin_lock(&dist->lock);



	/*

	 * We iterate over all VCPUs to find the MPIDRs matching the request.

	 * If we have handled one CPU, we clear it's bit to detect early

	 * if we are already finished. This avoids iterating through all

	 * VCPUs when most of the times we just signal a single VCPU.

	 */

	kvm_for_each_vcpu(c, c_vcpu, kvm) {



		/* Exit early if we have dealt with all requested CPUs */

		if (!broadcast && target_cpus == 0)

			break;



		 /* Don't signal the calling VCPU */

		if (broadcast && c == vcpu_id)

			continue;



		if (!broadcast) {

			int level0;



			level0 = match_mpidr(mpidr, target_cpus, c_vcpu);

			if (level0 == -1)

				continue;



			/* remove this matching VCPU from the mask */

			target_cpus &= ~BIT(level0);

		}



		/* Flag the SGI as pending */

		vgic_dist_irq_set_pending(c_vcpu, sgi);

		updated = 1;

		kvm_debug("SGI%d from CPU%d to CPU%d\n", sgi, vcpu_id, c);

	}

	if (updated)

		vgic_update_state(vcpu->kvm);

	spin_unlock(&dist->lock);

	if (updated)

		vgic_kick_vcpus(vcpu->kvm);

}



static int vgic_v3_create(struct kvm_device *dev, u32 type)

{

	return kvm_vgic_create(dev->kvm, type);