On 12/21/2010 01:37 PM, Konrad Rzeszutek Wilk wrote:
> We were not properly taking under advisement the 1-1 mappings
> when a large area of memory was ballooned out.
Could you expand on this? What does it mean?
J
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
> arch/x86/xen/mmu.c | 13 ++++++++-----
> 1 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index bd02e7d..92f4fec 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -464,7 +464,7 @@ static void free_p2m_page(void *p)
> static bool alloc_p2m(unsigned long pfn)
> {
> unsigned topidx, mididx;
> - unsigned long ***top_p, **mid;
> + unsigned long ***top_p, **mid, **mid_orig;
> unsigned long *top_mfn_p, *mid_mfn;
>
> topidx = p2m_top_index(pfn);
> @@ -473,15 +473,16 @@ static bool alloc_p2m(unsigned long pfn)
> top_p = &p2m_top[topidx];
> mid = *top_p;
>
> - if (mid == p2m_mid_identity) {
> + if (mid == p2m_mid_identity || mid == p2m_mid_missing) {
> /* Mid level is missing, allocate a new one */
> + mid_orig = mid;
> mid = alloc_p2m_page();
> if (!mid)
> return false;
>
> p2m_mid_init(mid, p2m_identity);
>
> - if (cmpxchg(top_p, p2m_mid_identity, mid) != p2m_mid_identity)
> + if (cmpxchg(top_p, mid_orig, mid) != mid_orig)
> free_p2m_page(mid);
> }
>
> @@ -510,9 +511,11 @@ static bool alloc_p2m(unsigned long pfn)
> p2m_top_mfn_p[topidx] = mid_mfn;
> }
>
> - if (p2m_top[topidx][mididx] == p2m_identity) {
> + if (p2m_top[topidx][mididx] == p2m_identity ||
> + p2m_top[topidx][mididx] == p2m_missing) {
> /* p2m leaf page is missing */
> unsigned long *p2m;
> + unsigned long *p2m_orig = p2m_top[topidx][mididx];
>
> p2m = alloc_p2m_page();
> if (!p2m)
> @@ -520,7 +523,7 @@ static bool alloc_p2m(unsigned long pfn)
>
> p2m_init(p2m);
>
> - if (cmpxchg(&mid[mididx], p2m_identity, p2m) != p2m_identity)
> + if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig)
> free_p2m_page(p2m);
> else
> mid_mfn[mididx] = virt_to_mfn(p2m);
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