linux-kernel - Re: [PATCH 11/22] KVM: x86: hyper-v: replace bitmap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sun, 22 May 2022 07:53:57 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Yury Norov <yury.norov@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        David Laight <David.Laight@...LAB.COM>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Joe Perches <joe@...ches.com>,
        Julia Lawall <Julia.Lawall@...ia.fr>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Nicholas Piggin <npiggin@...il.com>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Peter Zijlstra <peterz@...radead.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Matti Vaittinen <Matti.Vaittinen@...rohmeurope.com>,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H . Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>, kvm@...r.kernel.org,
        x86@...nel.org
Subject: Re: [PATCH 11/22] KVM: x86: hyper-v: replace bitmap_weight() with
 hweight64()

On Tue, May 10, 2022 at 08:47:39AM -0700, Yury Norov wrote:
> kvm_hv_flush_tlb() applies bitmap API to a u64 variable valid_bank_mask.
> Since valid_bank_mask has a fixed size, we can use hweight64() and avoid
> excessive bloating.

In kvm_hv_send_ipi(), valid_bank_mask is unsigned long, not u64.

This results in:

arch/x86/kvm/hyperv.c: In function 'kvm_hv_send_ipi':
include/asm-generic/bitops/const_hweight.h:21:76: error: right shift count >= width of type

on all 32-bit builds.

Guenter

> 
> CC: Borislav Petkov <bp@...en8.de>
> CC: Dave Hansen <dave.hansen@...ux.intel.com>
> CC: H. Peter Anvin <hpa@...or.com>
> CC: Ingo Molnar <mingo@...hat.com>
> CC: Jim Mattson <jmattson@...gle.com>
> CC: Joerg Roedel <joro@...tes.org>
> CC: Paolo Bonzini <pbonzini@...hat.com>
> CC: Sean Christopherson <seanjc@...gle.com>
> CC: Thomas Gleixner <tglx@...utronix.de>
> CC: Vitaly Kuznetsov <vkuznets@...hat.com>
> CC: Wanpeng Li <wanpengli@...cent.com>
> CC: kvm@...r.kernel.org
> CC: linux-kernel@...r.kernel.org
> CC: x86@...nel.org
> Signed-off-by: Yury Norov <yury.norov@...il.com>
> ---
>  arch/x86/kvm/hyperv.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index 41585f0edf1e..b652b856df2b 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -1855,7 +1855,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
>  		all_cpus = flush_ex.hv_vp_set.format !=
>  			HV_GENERIC_SET_SPARSE_4K;
>  
> -		if (hc->var_cnt != bitmap_weight((unsigned long *)&valid_bank_mask, 64))
> +		if (hc->var_cnt != hweight64(valid_bank_mask))
>  			return HV_STATUS_INVALID_HYPERCALL_INPUT;
>  
>  		if (all_cpus)
> @@ -1956,7 +1956,7 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
>  		valid_bank_mask = send_ipi_ex.vp_set.valid_bank_mask;
>  		all_cpus = send_ipi_ex.vp_set.format == HV_GENERIC_SET_ALL;
>  
> -		if (hc->var_cnt != bitmap_weight(&valid_bank_mask, 64))
> +		if (hc->var_cnt != hweight64(valid_bank_mask))
>  			return HV_STATUS_INVALID_HYPERCALL_INPUT;
>  
>  		if (all_cpus)
> -- 
> 2.32.0
>