Commit e8679fed authored by James Morse's avatar James Morse Committed by Marc Zyngier
Browse files

KVM: arm64: Stop save/restoring ACTLR_EL1 



KVM sets HCR_EL2.TACR via HCR_GUEST_FLAGS. This means ACTLR* accesses
from the guest are always trapped, and always return the value in the
sys_regs array.

The guest can't change the value of these registers, so we are
save restoring the reset value, which came from the host.

Stop save/restoring this register. Keep the storage for this register
in sys_regs[] as this is how the value is exposed to user-space,
removing it would break migration.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200529150656.7339-4-james.morse@arm.com
parent ef5a294b

arch/arm64/kvm/hyp/sysreg-sr.c

+0 −2
Original line number Diff line number Diff line
@@ -39,7 +39,6 @@ static void __hyp_text __sysreg_save_el1_state(struct kvm_cpu_context *ctxt) 
{

	ctxt->sys_regs[CSSELR_EL1]	= read_sysreg(csselr_el1);

	ctxt->sys_regs[SCTLR_EL1]	= read_sysreg_el1(SYS_SCTLR);

	ctxt->sys_regs[ACTLR_EL1]	= read_sysreg(actlr_el1);

	ctxt->sys_regs[CPACR_EL1]	= read_sysreg_el1(SYS_CPACR);

	ctxt->sys_regs[TTBR0_EL1]	= read_sysreg_el1(SYS_TTBR0);

	ctxt->sys_regs[TTBR1_EL1]	= read_sysreg_el1(SYS_TTBR1);
@@ -122,7 +121,6 @@ static void __hyp_text __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt) 
		isb();

	}



	write_sysreg(ctxt->sys_regs[ACTLR_EL1],		actlr_el1);

	write_sysreg_el1(ctxt->sys_regs[CPACR_EL1],	SYS_CPACR);

	write_sysreg_el1(ctxt->sys_regs[TTBR0_EL1],	SYS_TTBR0);

	write_sysreg_el1(ctxt->sys_regs[TTBR1_EL1],	SYS_TTBR1);

arch/arm64/kvm/sys_regs.c

+0 −2
Original line number Diff line number Diff line
@@ -78,7 +78,6 @@ static bool __vcpu_read_sys_reg_from_cpu(int reg, u64 *val) 
	switch (reg) {

	case CSSELR_EL1:	*val = read_sysreg_s(SYS_CSSELR_EL1);	break;

	case SCTLR_EL1:		*val = read_sysreg_s(SYS_SCTLR_EL12);	break;

	case ACTLR_EL1:		*val = read_sysreg_s(SYS_ACTLR_EL1);	break;

	case CPACR_EL1:		*val = read_sysreg_s(SYS_CPACR_EL12);	break;

	case TTBR0_EL1:		*val = read_sysreg_s(SYS_TTBR0_EL12);	break;

	case TTBR1_EL1:		*val = read_sysreg_s(SYS_TTBR1_EL12);	break;
@@ -118,7 +117,6 @@ static bool __vcpu_write_sys_reg_to_cpu(u64 val, int reg) 
	switch (reg) {

	case CSSELR_EL1:	write_sysreg_s(val, SYS_CSSELR_EL1);	break;

	case SCTLR_EL1:		write_sysreg_s(val, SYS_SCTLR_EL12);	break;

	case ACTLR_EL1:		write_sysreg_s(val, SYS_ACTLR_EL1);	break;

	case CPACR_EL1:		write_sysreg_s(val, SYS_CPACR_EL12);	break;

	case TTBR0_EL1:		write_sysreg_s(val, SYS_TTBR0_EL12);	break;

	case TTBR1_EL1:		write_sysreg_s(val, SYS_TTBR1_EL12);	break;

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