From: WANG Xuerui <kernel@xen0n.name>
To: Paolo Bonzini <pbonzini@redhat.com>, Huacai Chen <chenhuacai@kernel.org>
Cc: Tianrui Zhao <zhaotianrui@loongson.cn>,
Bibo Mao <maobibo@loongson.cn>,
kvm@vger.kernel.org, loongarch@lists.linux.dev,
linux-kernel@vger.kernel.org, WANG Xuerui <git@xen0n.name>
Subject: [PATCH RESEND for-6.8 v3 3/3] LoongArch: KVM: Streamline kvm_check_cpucfg and improve comments
Date: Fri, 16 Feb 2024 17:37:59 +0800 [thread overview]
Message-ID: <20240216093759.3038760-4-kernel@xen0n.name> (raw)
In-Reply-To: <20240216093759.3038760-1-kernel@xen0n.name>
From: WANG Xuerui <git@xen0n.name>
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.
Signed-off-by: WANG Xuerui <git@xen0n.name>
---
arch/loongarch/kvm/vcpu.c | 42 +++++++++++++++++++--------------------
1 file changed, 20 insertions(+), 22 deletions(-)
diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index e5acd4c08071..a241db6d77a6 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -302,20 +302,16 @@ 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;
@@ -345,24 +341,26 @@ 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,
--
2.43.0
prev parent reply other threads:[~2024-02-16 9:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-16 9:37 [PATCH RESEND for-6.8 v3 0/3] KVM: LoongArch: Fix wrong CPUCFG ID handling WANG Xuerui
2024-02-16 9:37 ` [PATCH RESEND for-6.8 v3 1/3] LoongArch: KVM: Fix input validation of _kvm_get_cpucfg and kvm_check_cpucfg WANG Xuerui
2024-02-16 9:37 ` [PATCH RESEND for-6.8 v3 2/3] LoongArch: KVM: Rename _kvm_get_cpucfg to _kvm_get_cpucfg_mask WANG Xuerui
2024-02-16 9:37 ` WANG Xuerui [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240216093759.3038760-4-kernel@xen0n.name \
--to=kernel@xen0n.name \
--cc=chenhuacai@kernel.org \
--cc=git@xen0n.name \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=loongarch@lists.linux.dev \
--cc=maobibo@loongson.cn \
--cc=pbonzini@redhat.com \
--cc=zhaotianrui@loongson.cn \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).