linux-kernel - Re: [PATCH] KVM: x86: Only advertise KVM_CAP_READONLY

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]

Message-ID: <y2vqv2k6b3ytwgvxkhl3jlxx2lpfcla6zigccuo426zp63lqgl@zvdztkpwuxed>
Date: Fri, 6 Sep 2024 12:11:19 -0700
From: Shakeel Butt <shakeel.butt@...ux.dev>
To: Tom Dohrmann <erbse.13@....de>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Michael Roth <michael.roth@....com>
Subject: Re: [PATCH] KVM: x86: Only advertise KVM_CAP_READONLY_MEM when
 supported by VM

On Mon, Sep 02, 2024 at 02:42:19PM GMT, Tom Dohrmann wrote:
> Until recently, KVM_CAP_READONLY_MEM was unconditionally supported on
> x86, but this is no longer the case for SEV-ES and SEV-SNP VMs.
> 
> When KVM_CHECK_EXTENSION is invoked on a VM, only advertise
> KVM_CAP_READONLY_MEM when it's actually supported.
> 
> Fixes: 66155de93bcf ("KVM: x86: Disallow read-only memslots for SEV-ES and SEV-SNP (and TDX)")
> Cc: Sean Christopherson <seanjc@...gle.com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Michael Roth <michael.roth@....com>
> Signed-off-by: Tom Dohrmann <erbse.13@....de>
> ---
>  arch/x86/kvm/x86.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 70219e406987..9ad7fe279e72 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4656,7 +4656,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_ASYNC_PF_INT:
>  	case KVM_CAP_GET_TSC_KHZ:
>  	case KVM_CAP_KVMCLOCK_CTRL:
> -	case KVM_CAP_READONLY_MEM:
>  	case KVM_CAP_IOAPIC_POLARITY_IGNORED:
>  	case KVM_CAP_TSC_DEADLINE_TIMER:
>  	case KVM_CAP_DISABLE_QUIRKS:
> @@ -4815,6 +4814,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_VM_TYPES:
>  		r = kvm_caps.supported_vm_types;
>  		break;
> +	case KVM_CAP_READONLY_MEM:
> +		r = kvm ? kvm_arch_has_readonly_mem(kvm) : 1;

Need a break here otherwise -Wimplicit-fallthrough option will warn.

>  	default:
>  		break;
>  	}
> --
> 2.34.1