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Commit 0c0543a1 authored by Andrew Jones's avatar Andrew Jones Committed by Christoffer Dall
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arm64: KVM: Hide PMU from guests when disabled 



Since commit 93390c0a ("arm64: KVM: Hide unsupported AArch64 CPU
features from guests") we can hide cpu features from guests. Apply
this to a long standing issue where guests see a PMU available, but
it's not, because it was not enabled by KVM's userspace.

Signed-off-by: default avatarAndrew Jones <drjones@redhat.com>
Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
parent 50c4c4e2

arch/arm64/kvm/sys_regs.c

+21 −14
Original line number Diff line number Diff line
@@ -881,18 +881,25 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu, 
}



/* Read a sanitised cpufeature ID register by sys_reg_desc */

static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)

static u64 read_id_reg(struct kvm_vcpu *vcpu,

		       struct sys_reg_desc const *r,

		       bool raz)

{

	u32 id = sys_reg((u32)r->Op0, (u32)r->Op1,

			 (u32)r->CRn, (u32)r->CRm, (u32)r->Op2);

	u64 val = raz ? 0 : read_sanitised_ftr_reg(id);



	if (id == SYS_ID_AA64PFR0_EL1) {

	switch (id) {

	case SYS_ID_AA64DFR0_EL1:

		if (!kvm_arm_pmu_v3_ready(vcpu))

			val &= ~(0xfUL << ID_AA64DFR0_PMUVER_SHIFT);

		break;

	case SYS_ID_AA64PFR0_EL1:

		if (val & (0xfUL << ID_AA64PFR0_SVE_SHIFT))

			pr_err_once("kvm [%i]: SVE unsupported for guests, suppressing\n",

				    task_pid_nr(current));



		val &= ~(0xfUL << ID_AA64PFR0_SVE_SHIFT);

		break;

	}



	return val;
@@ -908,7 +915,7 @@ static bool __access_id_reg(struct kvm_vcpu *vcpu, 
	if (p->is_write)

		return write_to_read_only(vcpu, p, r);



	p->regval = read_id_reg(r, raz);

	p->regval = read_id_reg(vcpu, r, raz);

	return true;

}
@@ -937,17 +944,17 @@ static u64 sys_reg_to_index(const struct sys_reg_desc *reg); 
 * are stored, and for set_id_reg() we don't allow the effective value

 * to be changed.

 */

static int __get_id_reg(const struct sys_reg_desc *rd, void __user *uaddr,

			bool raz)

static int __get_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,

			void __user *uaddr, bool raz)

{

	const u64 id = sys_reg_to_index(rd);

	const u64 val = read_id_reg(rd, raz);

	const u64 val = read_id_reg(vcpu, rd, raz);



	return reg_to_user(uaddr, &val, id);

}



static int __set_id_reg(const struct sys_reg_desc *rd, void __user *uaddr,

			bool raz)

static int __set_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,

			void __user *uaddr, bool raz)

{

	const u64 id = sys_reg_to_index(rd);

	int err;
@@ -958,7 +965,7 @@ static int __set_id_reg(const struct sys_reg_desc *rd, void __user *uaddr, 
		return err;



	/* This is what we mean by invariant: you can't change it. */

	if (val != read_id_reg(rd, raz))

	if (val != read_id_reg(vcpu, rd, raz))

		return -EINVAL;



	return 0;
@@ -967,25 +974,25 @@ static int __set_id_reg(const struct sys_reg_desc *rd, void __user *uaddr, 
static int get_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,

		      const struct kvm_one_reg *reg, void __user *uaddr)

{

	return __get_id_reg(rd, uaddr, false);

	return __get_id_reg(vcpu, rd, uaddr, false);

}



static int set_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,

		      const struct kvm_one_reg *reg, void __user *uaddr)

{

	return __set_id_reg(rd, uaddr, false);

	return __set_id_reg(vcpu, rd, uaddr, false);

}



static int get_raz_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,

			  const struct kvm_one_reg *reg, void __user *uaddr)

{

	return __get_id_reg(rd, uaddr, true);

	return __get_id_reg(vcpu, rd, uaddr, true);

}



static int set_raz_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,

			  const struct kvm_one_reg *reg, void __user *uaddr)

{

	return __set_id_reg(rd, uaddr, true);

	return __set_id_reg(vcpu, rd, uaddr, true);

}



/* sys_reg_desc initialiser for known cpufeature ID registers */