Commit 280b748e authored by Jintack Lim's avatar Jintack Lim Committed by Oliver Upton
Browse files

KVM: arm64: nv: Emulate EL12 register accesses from the virtual EL2 



With HCR_EL2.NV bit set, accesses to EL12 registers in the virtual EL2
trap to EL2. Handle those traps just like we do for EL1 registers.

One exception is CNTKCTL_EL12. We don't trap on CNTKCTL_EL1 for non-VHE
virtual EL2 because we don't have to. However, accessing CNTKCTL_EL12
will trap since it's one of the EL12 registers controlled by HCR_EL2.NV
bit.  Therefore, add a handler for it and don't treat it as a
non-trap-registers when preparing a shadow context.

These registers, being only a view on their EL1 counterpart, are
permanently hidden from userspace.

Reviewed-by: default avatarAlexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: default avatarJintack Lim <jintack.lim@linaro.org>
[maz: EL12_REG(), register visibility]
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230209175820.1939006-17-maz@kernel.org


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent e6b367db

arch/arm64/kvm/sys_regs.c

+37 −0
Original line number Diff line number Diff line
@@ -1482,6 +1482,26 @@ static unsigned int el2_visibility(const struct kvm_vcpu *vcpu, 
	.val = v,				\

}



/*

 * EL{0,1}2 registers are the EL2 view on an EL0 or EL1 register when

 * HCR_EL2.E2H==1, and only in the sysreg table for convenience of

 * handling traps. Given that, they are always hidden from userspace.

 */

static unsigned int elx2_visibility(const struct kvm_vcpu *vcpu,

				    const struct sys_reg_desc *rd)

{

	return REG_HIDDEN_USER;

}



#define EL12_REG(name, acc, rst, v) {		\

	SYS_DESC(SYS_##name##_EL12),		\

	.access = acc,				\

	.reset = rst,				\

	.reg = name##_EL1,			\

	.val = v,				\

	.visibility = elx2_visibility,		\

}



/* sys_reg_desc initialiser for known cpufeature ID registers */

#define ID_SANITISED(name) {			\

	SYS_DESC(SYS_##name),			\
@@ -2031,6 +2051,23 @@ static const struct sys_reg_desc sys_reg_descs[] = { 
	EL2_REG(CNTVOFF_EL2, access_rw, reset_val, 0),

	EL2_REG(CNTHCTL_EL2, access_rw, reset_val, 0),



	EL12_REG(SCTLR, access_vm_reg, reset_val, 0x00C50078),

	EL12_REG(CPACR, access_rw, reset_val, 0),

	EL12_REG(TTBR0, access_vm_reg, reset_unknown, 0),

	EL12_REG(TTBR1, access_vm_reg, reset_unknown, 0),

	EL12_REG(TCR, access_vm_reg, reset_val, 0),

	{ SYS_DESC(SYS_SPSR_EL12), access_spsr},

	{ SYS_DESC(SYS_ELR_EL12), access_elr},

	EL12_REG(AFSR0, access_vm_reg, reset_unknown, 0),

	EL12_REG(AFSR1, access_vm_reg, reset_unknown, 0),

	EL12_REG(ESR, access_vm_reg, reset_unknown, 0),

	EL12_REG(FAR, access_vm_reg, reset_unknown, 0),

	EL12_REG(MAIR, access_vm_reg, reset_unknown, 0),

	EL12_REG(AMAIR, access_vm_reg, reset_amair_el1, 0),

	EL12_REG(VBAR, access_rw, reset_val, 0),

	EL12_REG(CONTEXTIDR, access_vm_reg, reset_val, 0),

	EL12_REG(CNTKCTL, access_rw, reset_val, 0),



	EL2_REG(SP_EL2, NULL, reset_unknown, 0),

};