linux-kernel - Re: [PATCH 1/3] include files for kvmclock

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: <47341C4A.30508@redhat.com>
Date:	Fri, 09 Nov 2007 09:37:30 +0100
From:	Gerd Hoffmann <kraxel@...hat.com>
To:	Glauber de Oliveira Costa <gcosta@...hat.com>
CC:	linux-kernel@...r.kernel.org, jeremy@...p.org, avi@...ranet.com,
	aliguori@...ibm.com, kvm-devel@...ts.sourceforge.net,
	hollisb@...ibm.com
Subject: Re: [PATCH 1/3] include files for kvmclock

> +/*
> + * Guest has page alignment and padding requirements. At the host, it will
> + * only lead to wasted space at the vcpu struct. For this reason, the struct
> + * is not anonymous
> + */
> +union kvm_hv_clock {
> +	struct kvm_hv_clock_s {
> +		u64 tsc_mult;
> +		u64 now_ns;
> +		/* That's the wall clock, not the water closet */
> +		u64 wc_sec;
> +		u64 last_tsc;
> +		/* At first, we could use the tsc value as a marker, but Jeremy
> +		 * well noted that it will cause us locking problems in 32-bit
> +		 * sys, so we have a special version field */
> +		u32 version;
> +	} fields;
> +	char page_align[PAGE_SIZE];
> +};

What is the point in using a whole page per vcpu?  You probably don't
want struct kvm_hv_clock_s cross a page border.  Is that the only reason
or are there other constrains too?

As the kvm clock looks quite simliar to what xen does, how about making
the structs binary-compatible or simply reuse the xen version (struct
vcpu_time_info in xen/interface/xen.h)?

cheers,
  Gerd
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/