Commit f24adc65 authored by Oliver Upton's avatar Oliver Upton Committed by Marc Zyngier
Browse files

KVM: arm64: Allow guest to set the OSLK bit 



Allow writes to OSLAR and forward the OSLK bit to OSLSR. Do nothing with
the value for now.

Reviewed-by: default avatarReiji Watanabe <reijiw@google.com>
Signed-off-by: default avatarOliver Upton <oupton@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220203174159.2887882-4-oupton@google.com
parent d42e2671

arch/arm64/include/asm/sysreg.h

+3 −0
Original line number Diff line number Diff line
@@ -128,12 +128,15 @@ 
#define SYS_DBGWVRn_EL1(n)		sys_reg(2, 0, 0, n, 6)

#define SYS_DBGWCRn_EL1(n)		sys_reg(2, 0, 0, n, 7)

#define SYS_MDRAR_EL1			sys_reg(2, 0, 1, 0, 0)



#define SYS_OSLAR_EL1			sys_reg(2, 0, 1, 0, 4)

#define SYS_OSLAR_OSLK			BIT(0)



#define SYS_OSLSR_EL1			sys_reg(2, 0, 1, 1, 4)

#define SYS_OSLSR_OSLM_MASK		(BIT(3) | BIT(0))

#define SYS_OSLSR_OSLM_NI		0

#define SYS_OSLSR_OSLM_IMPLEMENTED	BIT(3)

#define SYS_OSLSR_OSLK			BIT(1)



#define SYS_OSDLR_EL1			sys_reg(2, 0, 1, 3, 4)

#define SYS_DBGPRCR_EL1			sys_reg(2, 0, 1, 4, 4)

arch/arm64/kvm/sys_regs.c

+30 −7
Original line number Diff line number Diff line
@@ -44,6 +44,10 @@ 
 * 64bit interface.

 */



static int reg_from_user(u64 *val, const void __user *uaddr, u64 id);

static int reg_to_user(void __user *uaddr, const u64 *val, u64 id);

static u64 sys_reg_to_index(const struct sys_reg_desc *reg);



static bool read_from_write_only(struct kvm_vcpu *vcpu,

				 struct sys_reg_params *params,

				 const struct sys_reg_desc *r)
@@ -287,6 +291,24 @@ static bool trap_loregion(struct kvm_vcpu *vcpu, 
	return trap_raz_wi(vcpu, p, r);

}



static bool trap_oslar_el1(struct kvm_vcpu *vcpu,

			   struct sys_reg_params *p,

			   const struct sys_reg_desc *r)

{

	u64 oslsr;



	if (!p->is_write)

		return read_from_write_only(vcpu, p, r);



	/* Forward the OSLK bit to OSLSR */

	oslsr = __vcpu_sys_reg(vcpu, OSLSR_EL1) & ~SYS_OSLSR_OSLK;

	if (p->regval & SYS_OSLAR_OSLK)

		oslsr |= SYS_OSLSR_OSLK;



	__vcpu_sys_reg(vcpu, OSLSR_EL1) = oslsr;

	return true;

}



static bool trap_oslsr_el1(struct kvm_vcpu *vcpu,

			   struct sys_reg_params *p,

			   const struct sys_reg_desc *r)
@@ -309,9 +331,14 @@ static int set_oslsr_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, 
	if (err)

		return err;



	if (val != rd->val)

	/*

	 * The only modifiable bit is the OSLK bit. Refuse the write if

	 * userspace attempts to change any other bit in the register.

	 */

	if ((val ^ rd->val) & ~SYS_OSLSR_OSLK)

		return -EINVAL;



	__vcpu_sys_reg(vcpu, rd->reg) = val;

	return 0;

}
@@ -1180,10 +1207,6 @@ static bool access_raz_id_reg(struct kvm_vcpu *vcpu, 
	return __access_id_reg(vcpu, p, r, true);

}



static int reg_from_user(u64 *val, const void __user *uaddr, u64 id);

static int reg_to_user(void __user *uaddr, const u64 *val, u64 id);

static u64 sys_reg_to_index(const struct sys_reg_desc *reg);



/* Visibility overrides for SVE-specific control registers */

static unsigned int sve_visibility(const struct kvm_vcpu *vcpu,

				   const struct sys_reg_desc *rd)
@@ -1463,7 +1486,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { 
	DBG_BCR_BVR_WCR_WVR_EL1(15),



	{ SYS_DESC(SYS_MDRAR_EL1), trap_raz_wi },

	{ SYS_DESC(SYS_OSLAR_EL1), trap_raz_wi },

	{ SYS_DESC(SYS_OSLAR_EL1), trap_oslar_el1 },

	{ SYS_DESC(SYS_OSLSR_EL1), trap_oslsr_el1, reset_val, OSLSR_EL1,

		SYS_OSLSR_OSLM_IMPLEMENTED, .set_user = set_oslsr_el1, },

	{ SYS_DESC(SYS_OSDLR_EL1), trap_raz_wi },
@@ -1937,7 +1960,7 @@ static const struct sys_reg_desc cp14_regs[] = { 


	DBGBXVR(0),

	/* DBGOSLAR */

	{ Op1( 0), CRn( 1), CRm( 0), Op2( 4), trap_raz_wi },

	{ Op1( 0), CRn( 1), CRm( 0), Op2( 4), trap_oslar_el1 },

	DBGBXVR(1),

	/* DBGOSLSR */

	{ Op1( 0), CRn( 1), CRm( 1), Op2( 4), trap_oslsr_el1, NULL, OSLSR_EL1 },