Commit 44226a3b authored by WANG Xuerui's avatar WANG Xuerui Committed by Xianglai Li
Browse files

LoongArch: KVM: Streamline kvm_check_cpucfg() and improve comments 

mainline inclusion
from mainline-v6.8-rc5
commit f0f5c4894f89bac9074b45bccc447c3659a0fa6f
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I94LRF


CVE: NA

--------------------------------

All the checks currently done in kvm_check_cpucfg can be realized with
early returns, so just do that to avoid extra cognitive burden related
to the return value handling.

While at it, clean up comments of _kvm_get_cpucfg_mask() and
kvm_check_cpucfg(), by removing comments that are merely restatement of
the code nearby, and paraphrasing the rest so they read more natural for
English speakers (that likely are not familiar with the actual Chinese-
influenced grammar).

No functional changes intended.

Reviewed-by: default avatarBibo Mao <maobibo@loongson.cn>
Signed-off-by: default avatarWANG Xuerui <git@xen0n.name>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
Signed-off-by: default avatarXianglai Li <lixianglai@loongson.cn>
parent caedd892

arch/loongarch/kvm/vcpu.c

+20 −22
Original line number Diff line number Diff line
@@ -305,20 +305,16 @@ static int _kvm_get_cpucfg_mask(int id, u64 *v) 


	switch (id) {

	case 2:

		/* Return CPUCFG2 features which have been supported by KVM */

		/* CPUCFG2 features unconditionally supported by KVM */

		*v = CPUCFG2_FP     | CPUCFG2_FPSP  | CPUCFG2_FPDP     |

		     CPUCFG2_FPVERS | CPUCFG2_LLFTP | CPUCFG2_LLFTPREV |

		     CPUCFG2_LAM;

		/*

		 * If LSX is supported by CPU, it is also supported by KVM,

		 * as we implement it.

		 * For the ISA extensions listed below, if one is supported

		 * by the host, then it is also supported by KVM.

		 */

		if (cpu_has_lsx)

			*v |= CPUCFG2_LSX;

		/*

		 * if LASX is supported by CPU, it is also supported by KVM,

		 * as we implement it.

		 */

		if (cpu_has_lasx)

			*v |= CPUCFG2_LASX;
@@ -349,24 +345,26 @@ static int kvm_check_cpucfg(int id, u64 val) 


	switch (id) {

	case 2:

		/* CPUCFG2 features checking */

		if (!(val & CPUCFG2_LLFTP))

			/* The LLFTP must be set, as guest must has a constant timer */

			ret = -EINVAL;

		else if ((val & CPUCFG2_FP) && (!(val & CPUCFG2_FPSP) || !(val & CPUCFG2_FPDP)))

			/* Single and double float point must both be set when enable FP */

			ret = -EINVAL;

		else if ((val & CPUCFG2_LSX) && !(val & CPUCFG2_FP))

			/* FP should be set when enable LSX */

			ret = -EINVAL;

		else if ((val & CPUCFG2_LASX) && !(val & CPUCFG2_LSX))

			/* LSX, FP should be set when enable LASX, and FP has been checked before. */

			ret = -EINVAL;

		break;

			/* Guests must have a constant timer */

			return -EINVAL;

		if ((val & CPUCFG2_FP) && (!(val & CPUCFG2_FPSP) || !(val & CPUCFG2_FPDP)))

			/* Single and double float point must both be set when FP is enabled */

			return -EINVAL;

		if ((val & CPUCFG2_LSX) && !(val & CPUCFG2_FP))

			/* LSX architecturally implies FP but val does not satisfy that */

			return -EINVAL;

		if ((val & CPUCFG2_LASX) && !(val & CPUCFG2_LSX))

			/* LASX architecturally implies LSX and FP but val does not satisfy that */

			return -EINVAL;

		return 0;

	default:

		break;

		/*

		 * Values for the other CPUCFG IDs are not being further validated

		 * besides the mask check above.

		 */

		return 0;

	}

	return ret;

}



static int kvm_get_one_reg(struct kvm_vcpu *vcpu,