On Wed, May 27, 2026 at 03:02:35PM +0000, Mostafa Saleh wrote:
From: Sebastian Ene sebastianene@google.com
Prevent the pKVM hypervisor from making assumptions that the endpoint memory access descriptor (EMAD) comes right after the FF-A memory region header. Prior to FF-A version 1.1 the header of the memory region didn't contain an offset to the endpoint memory access descriptor. The layout of a memory transaction looks like this from 1.1 onward: Type | Field name | Offset [ Header | ffa_mem_region | 0 EMAD 1 | ffa_mem_region_attributes) | ffa_mem_region.ep_mem_offset ] Verify that the offset to the first endpoint memory access descriptor is within the mailbox buffer bounds.
Also, fix one hardcoded sizeof(struct ffa_mem_region_attributes) that should be replaced ffa_emad_size_get() for compatibility with FFA v1.0.
[@Mostafa, Add missing call to ffa_rx_release() and use fraglen as the max buffer size as it is the only intialised part]
Fixes: 42fb33dde42b ("KVM: arm64: Use FF-A 1.1 with pKVM") Signed-off-by: Sebastian Ene sebastianene@google.com Signed-off-by: Mostafa Saleh smostafa@google.com
arch/arm64/kvm/hyp/nvhe/ffa.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c index b6cf9ad82e12..a12e01883314 100644 --- a/arch/arm64/kvm/hyp/nvhe/ffa.c +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c @@ -476,10 +476,10 @@ static void __do_ffa_mem_xfer(const u64 func_id, DECLARE_REG(u32, fraglen, ctxt, 2); DECLARE_REG(u64, addr_mbz, ctxt, 3); DECLARE_REG(u32, npages_mbz, ctxt, 4);
- u32 offset, nr_ranges, checked_offset, em_mem_access_off; struct ffa_mem_region_attributes *ep_mem_access; struct ffa_composite_mem_region *reg; struct ffa_mem_region *buf;
- u32 offset, nr_ranges, checked_offset; int ret = 0;
if (addr_mbz || npages_mbz || fraglen > len || @@ -489,7 +489,7 @@ static void __do_ffa_mem_xfer(const u64 func_id, }
Hi Mostafa,
if (fraglen < sizeof(struct ffa_mem_region) +
sizeof(struct ffa_mem_region_attributes)) {
ffa_emad_size_get(hyp_ffa_version)) {
Here sashiko complains about a compatibility break with v1.0 even though it is not from this change. This is because the size of sizeof(struct ffa_mem_region) was 36 bytes in v1.0 and now it is 48.
This check can cause "perfectly valid v1.0 memory transfers to be rejected" (from sashiko).
Other than that this looks good. I will spin a new version of this series.
@@ -508,8 +508,13 @@ static void __do_ffa_mem_xfer(const u64 func_id, buf = hyp_buffers.tx; memcpy(buf, host_buffers.tx, fraglen);
- ep_mem_access = (void *)buf +
ffa_mem_desc_offset(buf, 0, hyp_ffa_version);
- em_mem_access_off = ffa_mem_desc_offset(buf, 0, hyp_ffa_version);
- if ((u64)em_mem_access_off + ffa_emad_size_get(hyp_ffa_version) > fraglen) {
ret = FFA_RET_INVALID_PARAMETERS;goto out_unlock;- }
- ep_mem_access = (void *)buf + em_mem_access_off; offset = ep_mem_access->composite_off; if (!offset || buf->ep_count != 1 || buf->sender_id != HOST_FFA_ID) { ret = FFA_RET_INVALID_PARAMETERS;
@@ -574,9 +579,9 @@ static void do_ffa_mem_reclaim(struct arm_smccc_1_2_regs *res, DECLARE_REG(u32, handle_lo, ctxt, 1); DECLARE_REG(u32, handle_hi, ctxt, 2); DECLARE_REG(u32, flags, ctxt, 3);
- u32 offset, len, fraglen, fragoff, em_mem_access_off; struct ffa_mem_region_attributes *ep_mem_access; struct ffa_composite_mem_region *reg;
- u32 offset, len, fraglen, fragoff; struct ffa_mem_region *buf; int ret = 0; u64 handle;
@@ -599,8 +604,14 @@ static void do_ffa_mem_reclaim(struct arm_smccc_1_2_regs *res, len = res->a1; fraglen = res->a2;
- ep_mem_access = (void *)buf +
ffa_mem_desc_offset(buf, 0, hyp_ffa_version);
- em_mem_access_off = ffa_mem_desc_offset(buf, 0, hyp_ffa_version);
- if ((u64)em_mem_access_off + ffa_emad_size_get(hyp_ffa_version) > fraglen) {
ret = FFA_RET_INVALID_PARAMETERS;ffa_rx_release(res);goto out_unlock;- }
- ep_mem_access = (void *)buf + em_mem_access_off; offset = ep_mem_access->composite_off; /*
- We can trust the SPMD to get this right, but let's at least
-- 2.54.0.746.g67dd491aae-goog
Thanks, Sebastian