[PATCH 6.12 143/337] KVM: s390: pci: Validate AIBV and AISB before pinning guest pages

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Farhan Ali <[email protected]>

commit 868d32ac72cba21c5c6d8a66a814b7c25a3a5c01 upstream.

The AIBV holds one bit per MSI-X vector for a given function. The size of
the bit vector is derived from the NOI and the AIBVO. If the size of the
AIBV exceeds a single page boundary, then reject the request as we cannot
safely pin the guest AIBV.

Similarly reject the request if the AISB address is not 8-byte aligned as
the architecture requires doubleword alignment for the summary bit address.
Since the AISBO can address up to 64 bits, the size of the AISB can only be
8 bytes for the function. This also ensures the AISB doesn't exceed a
single page boundary.

Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
Cc: [email protected]
Reviewed-by: Christian Borntraeger <[email protected]>
Reviewed-by: Matthew Rosato <[email protected]>
Signed-off-by: Farhan Ali <[email protected]>
Tested-by: Matthew Rosato <[email protected]>
Signed-off-by: Christian Borntraeger <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 arch/s390/kvm/pci.c |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -225,7 +225,7 @@ static int kvm_s390_pci_aif_enable(struc
 				   bool assist)
 {
 	struct page *pages[1], *aibv_page, *aisb_page = NULL;
-	unsigned int msi_vecs, idx;
+	unsigned int msi_vecs, idx, size;
 	struct zpci_gaite *gaite;
 	unsigned long hva, bit;
 	struct kvm *kvm;
@@ -252,6 +252,14 @@ static int kvm_s390_pci_aif_enable(struc
 		return gisc;
 
 	/* Replace AIBV address */
+	size = BITS_TO_LONGS(msi_vecs + fib->fmt0.aibvo) * sizeof(unsigned long);
+	npages = DIV_ROUND_UP((fib->fmt0.aibv & ~PAGE_MASK) + size, PAGE_SIZE);
+	/* AIBV cannot span more than 1 page */
+	if (npages > 1) {
+		rc = -EINVAL;
+		goto out;
+	}
+
 	idx = srcu_read_lock(&kvm->srcu);
 	hva = gfn_to_hva(kvm, gpa_to_gfn((gpa_t)fib->fmt0.aibv));
 	npages = pin_user_pages_fast(hva, 1, FOLL_WRITE | FOLL_LONGTERM, pages);
@@ -267,6 +275,12 @@ static int kvm_s390_pci_aif_enable(struc
 
 	/* Pin the guest AISB if one was specified */
 	if (fib->fmt0.sum == 1) {
+		/* AISB must be dword aligned */
+		if (fib->fmt0.aisb & 0x7) {
+			rc = -EINVAL;
+			goto unpin1;
+		}
+
 		idx = srcu_read_lock(&kvm->srcu);
 		hva = gfn_to_hva(kvm, gpa_to_gfn((gpa_t)fib->fmt0.aisb));
 		npages = pin_user_pages_fast(hva, 1, FOLL_WRITE | FOLL_LONGTERM,