Hi Andrew,
On 21/09/2020 20:46, Andrew Cooper wrote:
On 21/09/2020 19:02, Julien Grall wrote:
From: Julien Grall <jgr...@amazon.com>
XENMEM_exchange can only be used by PV guest but the check is well
hidden in steal_page(). This is because paging_model_external() will
return false only for PV domain.
To make clearer this is PV only, add a check at the beginning of the
implementation. Take the opportunity to compile out the code if
CONFIG_PV is not set.
This change will also help a follow-up patch where the gmfn_mfn() will
be completely removed on arch not supporting the M2P.
Signed-off-by: Julien Grall <jgr...@amazon.com>
---
Jan suggested to #ifdef anything after the check to is_pv_domain().
However, it means to have two block of #ifdef as we can't mix
declaration and code.
I am actually thinking to move the implementation outside of mm.c in
possibly arch/x86 or a pv specific directory under common. Any opinion?
arch/x86/pv/mm.c, with the case XENMEM_exchange: moving into
arch_memory_op().
However, making this happen is incredibly tangled, and we're years
overdue a fix here.
Lets go with this for now, and tidying up can come later.
Acked-by: Andrew Cooper <andrew.coop...@citrix.com>, however...
Thanks!
Changes in v4:
- Patch added
---
xen/common/memory.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 714077c1e597..9300104943b0 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -504,6 +504,7 @@ static bool propagate_node(unsigned int xmf, unsigned int
*memflags)
static long memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
{
+#ifdef CONFIG_PV
struct xen_memory_exchange exch;
PAGE_LIST_HEAD(in_chunk_list);
PAGE_LIST_HEAD(out_chunk_list);
@@ -516,6 +517,9 @@ static long
memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
struct domain *d;
struct page_info *page;
+ if ( !is_pv_domain(d) )
+ return -EOPNOTSUPP;
+
if ( copy_from_guest(&exch, arg, 1) )
return -EFAULT;
@@ -797,6 +801,9 @@ static long memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
... there are now a load of #ifdef CONFIG_X86 between these two hunks
which can be dropped.
I didn't drop them because I wasn't sure whether we wanted to cater
future arch.
Anyway, I am happy to do the cleanup :).
Cheers,
--
Julien Grall
