From: Randy Dunlap <rdunlap@infradead.org>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: Fix BUILD_BUG() in __cpuid_entry_get_reg() w/ CONFIG_UBSAN=y
Date: Wed, 25 Mar 2020 12:21:00 -0700 [thread overview]
Message-ID: <6be637a8-77d3-3fda-238c-2e992307745f@infradead.org> (raw)
In-Reply-To: <20200325191259.23559-1-sean.j.christopherson@intel.com>
On 3/25/20 12:12 PM, Sean Christopherson wrote:
> Take the target reg in __cpuid_entry_get_reg() instead of a pointer to a
> struct cpuid_reg. When building with -fsanitize=alignment (enabled by
> CONFIG_UBSAN=y), some versions of gcc get tripped up on the pointer and
> trigger the BUILD_BUG().
>
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Fixes: d8577a4c238f8 ("KVM: x86: Do host CPUID at load time to mask KVM cpu caps")
> Fixes: 4c61534aaae2a ("KVM: x86: Introduce cpuid_entry_{get,has}() accessors")
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
LGTM. Thanks.
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
> ---
> arch/x86/kvm/cpuid.c | 2 +-
> arch/x86/kvm/cpuid.h | 8 ++++----
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 08280d8a2ac9..16d3ae432420 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -269,7 +269,7 @@ static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask)
> cpuid_count(cpuid.function, cpuid.index,
> &entry.eax, &entry.ebx, &entry.ecx, &entry.edx);
>
> - kvm_cpu_caps[leaf] &= *__cpuid_entry_get_reg(&entry, &cpuid);
> + kvm_cpu_caps[leaf] &= *__cpuid_entry_get_reg(&entry, cpuid.reg);
> }
>
> void kvm_set_cpu_caps(void)
> diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
> index 23b4cd1ad986..63a70f6a3df3 100644
> --- a/arch/x86/kvm/cpuid.h
> +++ b/arch/x86/kvm/cpuid.h
> @@ -99,9 +99,9 @@ static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_featu
> }
>
> static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
> - const struct cpuid_reg *cpuid)
> + u32 reg)
> {
> - switch (cpuid->reg) {
> + switch (reg) {
> case CPUID_EAX:
> return &entry->eax;
> case CPUID_EBX:
> @@ -121,7 +121,7 @@ static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
> {
> const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature);
>
> - return __cpuid_entry_get_reg(entry, &cpuid);
> + return __cpuid_entry_get_reg(entry, cpuid.reg);
> }
>
> static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry,
> @@ -189,7 +189,7 @@ static __always_inline u32 *guest_cpuid_get_register(struct kvm_vcpu *vcpu,
> if (!entry)
> return NULL;
>
> - return __cpuid_entry_get_reg(entry, &cpuid);
> + return __cpuid_entry_get_reg(entry, cpuid.reg);
> }
>
> static __always_inline bool guest_cpuid_has(struct kvm_vcpu *vcpu,
>
--
~Randy
next prev parent reply other threads:[~2020-03-25 19:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 19:12 [PATCH] KVM: x86: Fix BUILD_BUG() in __cpuid_entry_get_reg() w/ CONFIG_UBSAN=y Sean Christopherson
2020-03-25 19:21 ` Randy Dunlap [this message]
2020-03-31 14:51 ` Paolo Bonzini
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=6be637a8-77d3-3fda-238c-2e992307745f@infradead.org \
--to=rdunlap@infradead.org \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=sean.j.christopherson@intel.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
/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 NNTP newsgroup(s).