[Qemu-devel] [PATCH] spapr_pci: Fix number of returned vectors in ibm, change-msi

[Alexey Kardashevskiy <aik@ozlabs.ru>]

Current guest kernels try allocating as many vectors as the quota is.
For example, in the case of virtio-net (which has just 3 vectors)
the guest requests 4 vectors (that is the quota in the test) and
the existing ibm,change-msi handler returns 4. But before it returns,
it calls msix_set_message() in a loop and corrupts memory behind
the end of msix_table.

This limits the number of vectors returned by ibm,change-msi to
the maximum supported by the actual device.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---


This might go to 2.0 actually.


---
 hw/ppc/spapr_pci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index cbef095..cdfa369 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -343,6 +343,9 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, sPAPREnvironment *spapr,
 
     /* There is no cached config, allocate MSIs */
     if (!phb->msi_table[ndev].nvec) {
+        if (req_num > pdev->msix_entries_nr) {
+            req_num = pdev->msix_entries_nr;
+        }
         irq = spapr_allocate_irq_block(req_num, false,
                                        ret_intr_type == RTAS_TYPE_MSI);
         if (irq < 0) {
-- 
1.8.4.rc4