From 0a9f15fd56742b785ba4d06e64976f1f700b807c Mon Sep 17 00:00:00 2001 From: Quentin Perret Date: Tue, 23 May 2023 11:18:27 +0100 Subject: [PATCH] KVM: arm64: pkvm: Add support for fragmented FF-A descriptors FF-A memory descriptors may need to be sent in fragments when they don't fit in the mailboxes. Doing so involves using the FRAG_TX and FRAG_RX primitives defined in the FF-A protocol. Add support in the pKVM FF-A relayer for fragmented descriptors by monitoring outgoing FRAG_TX transactions and by buffering large descriptors on the reclaim path. Co-developed-by: Andrew Walbran Signed-off-by: Andrew Walbran Signed-off-by: Quentin Perret Signed-off-by: Will Deacon Link: https://lore.kernel.org/r/20230523101828.7328-11-will@kernel.org Signed-off-by: Oliver Upton --- arch/arm64/include/asm/kvm_pkvm.h | 17 +++- arch/arm64/kvm/hyp/nvhe/ffa.c | 170 ++++++++++++++++++++++++++++++++------ 2 files changed, 162 insertions(+), 25 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h index 2b495ec..e46250a0 100644 --- a/arch/arm64/include/asm/kvm_pkvm.h +++ b/arch/arm64/include/asm/kvm_pkvm.h @@ -6,7 +6,9 @@ #ifndef __ARM64_KVM_PKVM_H__ #define __ARM64_KVM_PKVM_H__ +#include #include +#include #include /* Maximum number of VMs that can co-exist under pKVM. */ @@ -110,8 +112,19 @@ static inline unsigned long host_s2_pgtable_pages(void) static inline unsigned long hyp_ffa_proxy_pages(void) { - /* A page each for the hypervisor's RX and TX mailboxes. */ - return 2 * KVM_FFA_MBOX_NR_PAGES; + size_t desc_max; + + /* + * The hypervisor FFA proxy needs enough memory to buffer a fragmented + * descriptor returned from EL3 in response to a RETRIEVE_REQ call. + */ + desc_max = sizeof(struct ffa_mem_region) + + sizeof(struct ffa_mem_region_attributes) + + sizeof(struct ffa_composite_mem_region) + + SG_MAX_SEGMENTS * sizeof(struct ffa_mem_region_addr_range); + + /* Plus a page each for the hypervisor's RX and TX mailboxes. */ + return (2 * KVM_FFA_MBOX_NR_PAGES) + DIV_ROUND_UP(desc_max, PAGE_SIZE); } #endif /* __ARM64_KVM_PKVM_H__ */ diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c index 926314a..58dcd92 100644 --- a/arch/arm64/kvm/hyp/nvhe/ffa.c +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c @@ -42,6 +42,18 @@ */ #define HOST_FFA_ID 0 +/* + * A buffer to hold the maximum descriptor size we can see from the host, + * which is required when the SPMD returns a fragmented FFA_MEM_RETRIEVE_RESP + * when resolving the handle on the reclaim path. + */ +struct kvm_ffa_descriptor_buffer { + void *buf; + size_t len; +}; + +static struct kvm_ffa_descriptor_buffer ffa_desc_buf; + struct kvm_ffa_buffers { hyp_spinlock_t lock; void *tx; @@ -122,6 +134,24 @@ static int ffa_unmap_hyp_buffers(void) return res.a0 == FFA_SUCCESS ? FFA_RET_SUCCESS : res.a2; } +static void ffa_mem_frag_tx(struct arm_smccc_res *res, u32 handle_lo, + u32 handle_hi, u32 fraglen, u32 endpoint_id) +{ + arm_smccc_1_1_smc(FFA_MEM_FRAG_TX, + handle_lo, handle_hi, fraglen, endpoint_id, + 0, 0, 0, + res); +} + +static void ffa_mem_frag_rx(struct arm_smccc_res *res, u32 handle_lo, + u32 handle_hi, u32 fragoff) +{ + arm_smccc_1_1_smc(FFA_MEM_FRAG_RX, + handle_lo, handle_hi, fragoff, HOST_FFA_ID, + 0, 0, 0, + res); +} + static void ffa_mem_xfer(struct arm_smccc_res *res, u64 func_id, u32 len, u32 fraglen) { @@ -327,6 +357,64 @@ static int ffa_host_unshare_ranges(struct ffa_mem_region_addr_range *ranges, return ret; } +static void do_ffa_mem_frag_tx(struct arm_smccc_res *res, + struct kvm_cpu_context *ctxt) +{ + DECLARE_REG(u32, handle_lo, ctxt, 1); + DECLARE_REG(u32, handle_hi, ctxt, 2); + DECLARE_REG(u32, fraglen, ctxt, 3); + DECLARE_REG(u32, endpoint_id, ctxt, 4); + struct ffa_mem_region_addr_range *buf; + int ret = FFA_RET_INVALID_PARAMETERS; + u32 nr_ranges; + + if (fraglen > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) + goto out; + + if (fraglen % sizeof(*buf)) + goto out; + + hyp_spin_lock(&host_buffers.lock); + if (!host_buffers.tx) + goto out_unlock; + + buf = hyp_buffers.tx; + memcpy(buf, host_buffers.tx, fraglen); + nr_ranges = fraglen / sizeof(*buf); + + ret = ffa_host_share_ranges(buf, nr_ranges); + if (ret) { + /* + * We're effectively aborting the transaction, so we need + * to restore the global state back to what it was prior to + * transmission of the first fragment. + */ + ffa_mem_reclaim(res, handle_lo, handle_hi, 0); + WARN_ON(res->a0 != FFA_SUCCESS); + goto out_unlock; + } + + ffa_mem_frag_tx(res, handle_lo, handle_hi, fraglen, endpoint_id); + if (res->a0 != FFA_SUCCESS && res->a0 != FFA_MEM_FRAG_RX) + WARN_ON(ffa_host_unshare_ranges(buf, nr_ranges)); + +out_unlock: + hyp_spin_unlock(&host_buffers.lock); +out: + if (ret) + ffa_to_smccc_res(res, ret); + + /* + * If for any reason this did not succeed, we're in trouble as we have + * now lost the content of the previous fragments and we can't rollback + * the host stage-2 changes. The pages previously marked as shared will + * remain stuck in that state forever, hence preventing the host from + * sharing/donating them again and may possibly lead to subsequent + * failures, but this will not compromise confidentiality. + */ + return; +} + static __always_inline void do_ffa_mem_xfer(const u64 func_id, struct arm_smccc_res *res, struct kvm_cpu_context *ctxt) @@ -337,8 +425,8 @@ static __always_inline void do_ffa_mem_xfer(const u64 func_id, DECLARE_REG(u32, npages_mbz, ctxt, 4); struct ffa_composite_mem_region *reg; struct ffa_mem_region *buf; + u32 offset, nr_ranges; int ret = 0; - u32 offset; BUILD_BUG_ON(func_id != FFA_FN64_MEM_SHARE && func_id != FFA_FN64_MEM_LEND); @@ -349,11 +437,6 @@ static __always_inline void do_ffa_mem_xfer(const u64 func_id, goto out; } - if (fraglen < len) { - ret = FFA_RET_ABORTED; - goto out; - } - if (fraglen < sizeof(struct ffa_mem_region) + sizeof(struct ffa_mem_region_attributes)) { ret = FFA_RET_INVALID_PARAMETERS; @@ -381,21 +464,26 @@ static __always_inline void do_ffa_mem_xfer(const u64 func_id, } reg = (void *)buf + offset; - if (fraglen < offset + sizeof(struct ffa_composite_mem_region) + - reg->addr_range_cnt * - sizeof(struct ffa_mem_region_addr_range)) { + nr_ranges = ((void *)buf + fraglen) - (void *)reg->constituents; + if (nr_ranges % sizeof(reg->constituents[0])) { ret = FFA_RET_INVALID_PARAMETERS; goto out_unlock; } - ret = ffa_host_share_ranges(reg->constituents, reg->addr_range_cnt); + nr_ranges /= sizeof(reg->constituents[0]); + ret = ffa_host_share_ranges(reg->constituents, nr_ranges); if (ret) goto out_unlock; ffa_mem_xfer(res, func_id, len, fraglen); - if (res->a0 != FFA_SUCCESS) { - WARN_ON(ffa_host_unshare_ranges(reg->constituents, - reg->addr_range_cnt)); + if (fraglen != len) { + if (res->a0 != FFA_MEM_FRAG_RX) + goto err_unshare; + + if (res->a3 != fraglen) + goto err_unshare; + } else if (res->a0 != FFA_SUCCESS) { + goto err_unshare; } out_unlock: @@ -404,6 +492,10 @@ out: if (ret) ffa_to_smccc_res(res, ret); return; + +err_unshare: + WARN_ON(ffa_host_unshare_ranges(reg->constituents, nr_ranges)); + goto out_unlock; } static void do_ffa_mem_reclaim(struct arm_smccc_res *res, @@ -413,9 +505,9 @@ static void do_ffa_mem_reclaim(struct arm_smccc_res *res, DECLARE_REG(u32, handle_hi, ctxt, 2); DECLARE_REG(u32, flags, ctxt, 3); struct ffa_composite_mem_region *reg; + u32 offset, len, fraglen, fragoff; struct ffa_mem_region *buf; int ret = 0; - u32 offset; u64 handle; handle = PACK_HANDLE(handle_lo, handle_hi); @@ -433,11 +525,8 @@ static void do_ffa_mem_reclaim(struct arm_smccc_res *res, if (res->a0 != FFA_MEM_RETRIEVE_RESP) goto out_unlock; - /* Check for fragmentation */ - if (res->a1 != res->a2) { - ret = FFA_RET_ABORTED; - goto out_unlock; - } + len = res->a1; + fraglen = res->a2; offset = buf->ep_mem_access[0].composite_off; /* @@ -445,16 +534,36 @@ static void do_ffa_mem_reclaim(struct arm_smccc_res *res, * check that we end up with something that doesn't look _completely_ * bogus. */ - if (WARN_ON(offset > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE)) { + if (WARN_ON(offset > len || + fraglen > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE)) { ret = FFA_RET_ABORTED; goto out_unlock; } - reg = (void *)buf + offset; + if (len > ffa_desc_buf.len) { + ret = FFA_RET_NO_MEMORY; + goto out_unlock; + } + + buf = ffa_desc_buf.buf; + memcpy(buf, hyp_buffers.rx, fraglen); + + for (fragoff = fraglen; fragoff < len; fragoff += fraglen) { + ffa_mem_frag_rx(res, handle_lo, handle_hi, fragoff); + if (res->a0 != FFA_MEM_FRAG_TX) { + ret = FFA_RET_INVALID_PARAMETERS; + goto out_unlock; + } + + fraglen = res->a3; + memcpy((void *)buf + fragoff, hyp_buffers.rx, fraglen); + } + ffa_mem_reclaim(res, handle_lo, handle_hi, flags); if (res->a0 != FFA_SUCCESS) goto out_unlock; + reg = (void *)buf + offset; /* If the SPMD was happy, then we should be too. */ WARN_ON(ffa_host_unshare_ranges(reg->constituents, reg->addr_range_cnt)); @@ -569,6 +678,9 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt) case FFA_FN64_MEM_LEND: do_ffa_mem_xfer(FFA_FN64_MEM_LEND, &res, host_ctxt); goto out_handled; + case FFA_MEM_FRAG_TX: + do_ffa_mem_frag_tx(&res, host_ctxt); + goto out_handled; } if (ffa_call_supported(func_id)) @@ -584,6 +696,7 @@ int hyp_ffa_init(void *pages) { struct arm_smccc_res res; size_t min_rxtx_sz; + void *tx, *rx; if (kvm_host_psci_config.smccc_version < ARM_SMCCC_VERSION_1_2) return 0; @@ -624,10 +737,21 @@ int hyp_ffa_init(void *pages) if (min_rxtx_sz > PAGE_SIZE) return -EOPNOTSUPP; + tx = pages; + pages += KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE; + rx = pages; + pages += KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE; + + ffa_desc_buf = (struct kvm_ffa_descriptor_buffer) { + .buf = pages, + .len = PAGE_SIZE * + (hyp_ffa_proxy_pages() - (2 * KVM_FFA_MBOX_NR_PAGES)), + }; + hyp_buffers = (struct kvm_ffa_buffers) { .lock = __HYP_SPIN_LOCK_UNLOCKED, - .tx = pages, - .rx = pages + (KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE), + .tx = tx, + .rx = rx, }; host_buffers = (struct kvm_ffa_buffers) { -- 2.7.4