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From: Oliver Upton To: Wei-Lin Chang Cc: Snehal Koukuntla , Marc Zyngier , James Morse , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Sudeep Holla , Sebastian Ene , Vincent Donnefort , Jean-Philippe Brucker , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3] KVM: arm64: Add memory length checks and remove inline in do_ffa_mem_xfer Message-ID: References: <20240909180154.3267939-1-snehalreddy@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240910_111853_618543_DB02E17C X-CRM114-Status: GOOD ( 33.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Sep 11, 2024 at 12:32:29AM +0800, Wei-Lin Chang wrote: > Hi everyone, > > On Mon, Sep 09, 2024 at 06:01:54PM GMT, Snehal Koukuntla wrote: > > When we share memory through FF-A and the description of the buffers > > exceeds the size of the mapped buffer, the fragmentation API is used. > > The fragmentation API allows specifying chunks of descriptors in subsequent > > FF-A fragment calls and no upper limit has been established for this. > > The entire memory region transferred is identified by a handle which can be > > used to reclaim the transferred memory. > > To be able to reclaim the memory, the description of the buffers has to fit > > in the ffa_desc_buf. > > Add a bounds check on the FF-A sharing path to prevent the memory reclaim > > from failing. > > > > Also do_ffa_mem_xfer() does not need __always_inline > > > > Fixes: 634d90cf0ac65 ("KVM: arm64: Handle FFA_MEM_LEND calls from the host") > > Cc: stable@vger.kernel.org > > Reviewed-by: Sebastian Ene > > Signed-off-by: Snehal Koukuntla > > --- > > arch/arm64/kvm/hyp/nvhe/ffa.c | 7 ++++++- > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c > > index e715c157c2c4..637425f63fd1 100644 > > --- a/arch/arm64/kvm/hyp/nvhe/ffa.c > > +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c > > @@ -426,7 +426,7 @@ static void do_ffa_mem_frag_tx(struct arm_smccc_res *res, > > return; > > } > > > > -static __always_inline void do_ffa_mem_xfer(const u64 func_id, > > +static void do_ffa_mem_xfer(const u64 func_id, > > I am seeing a compilation error because of this. Thanks for reporting this. Looks like the __always_inline was slightly more load bearing... Marc, can you put something like this on top? >From c2712eaa94989ae6457baad3ec459cf363ec5119 Mon Sep 17 00:00:00 2001 From: Oliver Upton Date: Tue, 10 Sep 2024 16:45:30 +0000 Subject: [PATCH] KVM: arm64: Drop BUILD_BUG_ON() from do_ffa_mem_xfer() __always_inline was recently discarded from do_ffa_mem_xfer() since it appeared to be unnecessary. Of course, this was ~immediately proven wrong, as the compile-time check against @func_id depends on inlining for the value to be known. Just downgrade to a WARN_ON() instead of putting the old mess back in place. Fix the wrapping/indentation of the function parameters while at it. Fixes: 39dacbeeee70 ("KVM: arm64: Add memory length checks and remove inline in do_ffa_mem_xfer") Reported-by: Wei-Lin Chang Signed-off-by: Oliver Upton --- arch/arm64/kvm/hyp/nvhe/ffa.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c index 637425f63fd1..316d269341f3 100644 --- a/arch/arm64/kvm/hyp/nvhe/ffa.c +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c @@ -426,9 +426,8 @@ static void do_ffa_mem_frag_tx(struct arm_smccc_res *res, return; } -static void do_ffa_mem_xfer(const u64 func_id, - struct arm_smccc_res *res, - struct kvm_cpu_context *ctxt) +static void do_ffa_mem_xfer(const u64 func_id, struct arm_smccc_res *res, + struct kvm_cpu_context *ctxt) { DECLARE_REG(u32, len, ctxt, 1); DECLARE_REG(u32, fraglen, ctxt, 2); @@ -440,8 +439,10 @@ static void do_ffa_mem_xfer(const u64 func_id, u32 offset, nr_ranges; int ret = 0; - BUILD_BUG_ON(func_id != FFA_FN64_MEM_SHARE && - func_id != FFA_FN64_MEM_LEND); + if (WARN_ON(func_id != FFA_FN64_MEM_SHARE && func_id != FFA_FN64_MEM_LEND)) { + ret = SMCCC_RET_NOT_SUPPORTED; + goto out; + } if (addr_mbz || npages_mbz || fraglen > len || fraglen > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) { -- 2.46.0.598.g6f2099f65c-goog -- Thanks, Oliver