Re: [kvm-unit-tests PATCH v3 1/3] s390x: pv: implement routine to share/unshare memory

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On 1/20/21 11:48 AM, Thomas Huth wrote:
On 19/01/2021 20.52, Pierre Morel wrote:
When communicating with the host we need to share part of
the memory.

Let's implement the ultravisor calls for this.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Suggested-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
Acked-by: Cornelia Huck <cohuck@xxxxxxxxxx>
---
  lib/s390x/asm/uv.h | 38 ++++++++++++++++++++++++++++++++++++++
  1 file changed, 38 insertions(+)

diff --git a/lib/s390x/asm/uv.h b/lib/s390x/asm/uv.h
index 4c2fc48..1242336 100644
--- a/lib/s390x/asm/uv.h
+++ b/lib/s390x/asm/uv.h
@@ -71,4 +71,42 @@ static inline int uv_call(unsigned long r1, unsigned long r2)
      return cc;
  }
+static inline int share(unsigned long addr, u16 cmd)
+{
+    struct uv_cb_share uvcb = {
+        .header.cmd = cmd,
+        .header.len = sizeof(uvcb),
+        .paddr = addr
+    };
+    int cc;
+
+    cc = uv_call(0, (u64)&uvcb);
+    if (!cc && (uvcb.header.rc == 0x0001))

You can drop the innermost parentheses.

OK.


+        return 0;
+
+    report_info("cc %d response code: %04x", cc, uvcb.header.rc);
+    return -1;
+}
+
+/*
+ * Guest 2 request to the Ultravisor to make a page shared with the
+ * hypervisor for IO.
+ *
+ * @addr: Real or absolute address of the page to be shared

When is it real, and when is it absolute?

It only depends on the prefixing, the call can use both.


+ */
+static inline int uv_set_shared(unsigned long addr)
+{
+    return share(addr, UVC_CMD_SET_SHARED_ACCESS);
+}
+
+/*
+ * Guest 2 request to the Ultravisor to make a page unshared.
+ *
+ * @addr: Real or absolute address of the page to be unshared

dito

+ */
+static inline int uv_remove_shared(unsigned long addr)
+{
+    return share(addr, UVC_CMD_REMOVE_SHARED_ACCESS);
+}
+
  #endif

Apart from the nits:
Acked-by: Thomas Huth <thuth@xxxxxxxxxx>


Thanks thomas for reviewing.

Regards,
Pierre


--
Pierre Morel
IBM Lab Boeblingen



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