[PATCH v8 5/6] KVM: arm64: Ensure FFA ranges are page aligned

[Sebastian Ene]

From: Mostafa Saleh <smostafa at google.com>

Harden the check for the constituent memory region page alignment
to prevent over-sharing when the negotiated FFA_PAGE_SIZE size is
smaller than the system PAGE_SIZE.
At the moment we only check that the size of the range is page
aligned, and truncate the address to the page boundary which can
annotate more memory than needed as being used by the FF-A.

Fixes: 436090001776 ("KVM: arm64: Handle FFA_MEM_SHARE calls from the host")
Signed-off-by: Mostafa Saleh <smostafa at google.com>
Reviewed-by: Vincent Donnefort <vdonnefort at google.com>
Signed-off-by: Sebastian Ene <sebastianene at google.com>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 14aa37846059..bb01d8f83056 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -352,7 +352,7 @@ static u32 __ffa_host_share_ranges(struct ffa_mem_region_addr_range *ranges,
 		u64 sz = (u64)range->pg_cnt * FFA_PAGE_SIZE;
 		u64 pfn = hyp_phys_to_pfn(range->address);
 
-		if (!PAGE_ALIGNED(sz))
+		if (!PAGE_ALIGNED(sz | range->address))
 			break;
 
 		if (__pkvm_host_share_ffa(pfn, sz / PAGE_SIZE))
@@ -372,7 +372,7 @@ static u32 __ffa_host_unshare_ranges(struct ffa_mem_region_addr_range *ranges,
 		u64 sz = (u64)range->pg_cnt * FFA_PAGE_SIZE;
 		u64 pfn = hyp_phys_to_pfn(range->address);
 
-		if (!PAGE_ALIGNED(sz))
+		if (!PAGE_ALIGNED(sz | range->address))
 			break;
 
 		if (__pkvm_host_unshare_ffa(pfn, sz / PAGE_SIZE))
-- 
2.55.0.rc0.799.gd6f94ed593-goog