linux-kernel - Re: [PATCH 4/6] xen/pvh: bootup and setup related changes.

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Date:	Mon, 22 Oct 2012 14:34:44 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	"mukesh.rathor@...cle.com" <mukesh.rathor@...cle.com>,
	Ian Campbell <Ian.Campbell@...rix.com>,
	Stefano Stabellini <Stefano.Stabellini@...citrix.com>
Subject: Re: [PATCH 4/6] xen/pvh: bootup and setup related changes.

On Sat, 20 Oct 2012, Konrad Rzeszutek Wilk wrote:
> From: Mukesh Rathor <mukesh.rathor@...cle.com>
> 
> In enlighten.c for PVH we can trap cpuid via vmexit, so don't
> need to use emulated prefix call. We also check for vector callback
> early on, as it is a required feature. PVH also runs at default kernel
> IOPL.
> 
> In setup.c, in xen_add_extra_mem() we can skip updating P2M as it's managed
> by Xen. PVH maps the entire IO space, but only RAM pages need to be repopulated.
> 
> Finally, pure PV settings are moved to a separate function that is only called
> for pure PV, ie, pv with pvmmu.
> 
> Signed-off-by: Mukesh Rathor <mukesh.rathor@...cle.com>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
>
> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> index 8971a26..8cce47b 100644
> --- a/arch/x86/xen/setup.c
> +++ b/arch/x86/xen/setup.c
> @@ -27,6 +27,7 @@
>  #include <xen/interface/memory.h>
>  #include <xen/interface/physdev.h>
>  #include <xen/features.h>
> +#include "mmu.h"
>  #include "xen-ops.h"
>  #include "vdso.h"
>  
> @@ -78,6 +79,9 @@ static void __init xen_add_extra_mem(u64 start, u64 size)
>  
>  	memblock_reserve(start, size);
>  
> +	if (xen_feature(XENFEAT_auto_translated_physmap))
> +		return;
> +
>  	xen_max_p2m_pfn = PFN_DOWN(start + size);
>  	for (pfn = PFN_DOWN(start); pfn < xen_max_p2m_pfn; pfn++) {
>  		unsigned long mfn = pfn_to_mfn(pfn);
> @@ -100,6 +104,7 @@ static unsigned long __init xen_do_chunk(unsigned long start,
>  		.domid        = DOMID_SELF
>  	};
>  	unsigned long len = 0;
> +	int xlated_phys = xen_feature(XENFEAT_auto_translated_physmap);
>  	unsigned long pfn;
>  	int ret;
>  
> @@ -113,7 +118,7 @@ static unsigned long __init xen_do_chunk(unsigned long start,
>  				continue;
>  			frame = mfn;
>  		} else {
> -			if (mfn != INVALID_P2M_ENTRY)
> +			if (!xlated_phys && mfn != INVALID_P2M_ENTRY)
>  				continue;
>  			frame = pfn;
>  		}

Shouldn't we add a "!xlated_phys &&" to the other case as well?
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