On 11/30/2015 01:06 PM, Paul Mackerras wrote:
On Tue, Sep 15, 2015 at 08:49:35PM +1000, Alexey Kardashevskiy wrote:
At the moment pages used for TCE tables (in addition to pages addressed
by TCEs) are not counted in locked_vm counter so a malicious userspace
tool can call ioctl(KVM_CREATE_SPAPR_TCE) as many times as RLIMIT_NOFILE and
lock a lot of memory.

This adds counting for pages used for TCE tables.

This counts the number of pages required for a table plus pages for
the kvmppc_spapr_tce_table struct (TCE table descriptor) itself.

This does not change the amount of (de)allocated memory.

Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
  arch/powerpc/kvm/book3s_64_vio.c | 51 +++++++++++++++++++++++++++++++++++++++-
  1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index 9526c34..b70787d 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -45,13 +45,56 @@ static long kvmppc_stt_npages(unsigned long window_size)
                     * sizeof(u64), PAGE_SIZE) / PAGE_SIZE;

+static long kvmppc_account_memlimit(long npages, bool inc)
+       long ret = 0;
+       const long bytes = sizeof(struct kvmppc_spapr_tce_table) +
+                       (abs(npages) * sizeof(struct page *));

Why abs(npages)?  Can npages be negative?  If so, what does that mean?

Leftover from older versions when there was one shared account_memlimit(long npages). It does not make sense here, I need to remove it.

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