[PATCH v2 04/10] KVM: arm64: Handle FFA_RXTX_MAP and FFA_RXTX_UNMAP calls from the host

Will Deacon
2023-04-19T12:22:14Z

Handle FFA_RXTX_MAP and FFA_RXTX_UNMAP calls from the host by sharing
the host's mailbox memory with the hypervisor and establishing a
separate pair of mailboxes between the hypervisor and the SPMD at EL3.

Co-developed-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kvm/hyp/nvhe/ffa.c | 184 ++++++++++++++++++++++++++++++++++
include/linux/arm_ffa.h | 8 ++
2 files changed, 192 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index de0fba79b195..9ee3be517e1e 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -31,6 +31,8 @@
#include <asm/kvm_pkvm.h>

#include <nvhe/ffa.h>
+#include <nvhe/mem_protect.h>
+#include <nvhe/memory.h>
#include <nvhe/trap_handler.h>
#include <nvhe/spinlock.h>

@@ -52,6 +54,7 @@ struct kvm_ffa_buffers {
* client.
*/
static struct kvm_ffa_buffers hyp_buffers;
+static struct kvm_ffa_buffers host_buffers;

static void ffa_to_smccc_error(struct arm_smccc_res *res, u64 ffa_errno)
{
@@ -61,6 +64,15 @@ static void ffa_to_smccc_error(struct arm_smccc_res *res, u64 ffa_errno)
};
}

+static void ffa_to_smccc_res(struct arm_smccc_res *res, int ret)
+{
+ if (ret == FFA_RET_SUCCESS) {
+ *res = (struct arm_smccc_res) { .a0 = FFA_SUCCESS };
+ } else {
+ ffa_to_smccc_error(res, ret);
+ }
+}
+
static void ffa_set_retval(struct kvm_cpu_context *ctxt,
struct arm_smccc_res *res)
{
@@ -78,6 +90,140 @@ static bool is_ffa_call(u64 func_id)
ARM_SMCCC_FUNC_NUM(func_id) <= FFA_MAX_FUNC_NUM;
}

+static int spmd_map_ffa_buffers(u64 ffa_page_count)
+{
+ struct arm_smccc_res res;
+
+ arm_smccc_1_1_smc(FFA_FN64_RXTX_MAP,
+ hyp_virt_to_phys(hyp_buffers.tx),
+ hyp_virt_to_phys(hyp_buffers.rx),
+ ffa_page_count,
+ 0, 0, 0, 0,
+ &res);
+
+ return res.a0 == FFA_SUCCESS ? FFA_RET_SUCCESS : res.a2;
+}
+
+static int spmd_unmap_ffa_buffers(void)
+{
+ struct arm_smccc_res res;
+
+ arm_smccc_1_1_smc(FFA_RXTX_UNMAP,
+ HOST_FFA_ID,
+ 0, 0, 0, 0, 0, 0,
+ &res);
+
+ return res.a0 == FFA_SUCCESS ? FFA_RET_SUCCESS : res.a2;
+}
+
+static void do_ffa_rxtx_map(struct arm_smccc_res *res,
+ struct kvm_cpu_context *ctxt)
+{
+ DECLARE_REG(phys_addr_t, tx, ctxt, 1);
+ DECLARE_REG(phys_addr_t, rx, ctxt, 2);
+ DECLARE_REG(u32, npages, ctxt, 3);
+ int ret = 0;
+ void *rx_virt, *tx_virt;
+
+ if (npages != (KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) / FFA_PAGE_SIZE) {
+ ret = FFA_RET_INVALID_PARAMETERS;
+ goto out;
+ }
+
+ if (!PAGE_ALIGNED(tx) || !PAGE_ALIGNED(rx)) {
+ ret = FFA_RET_INVALID_PARAMETERS;
+ goto out;
+ }
+
+ hyp_spin_lock(&host_buffers.lock);
+ if (host_buffers.tx) {
+ ret = FFA_RET_DENIED;
+ goto out_unlock;
+ }
+
+ ret = spmd_map_ffa_buffers(npages);
+ if (ret)
+ goto out_unlock;
+
+ ret = __pkvm_host_share_hyp(hyp_phys_to_pfn(tx));
+ if (ret) {
+ ret = FFA_RET_INVALID_PARAMETERS;
+ goto err_unmap;
+ }
+
+ ret = __pkvm_host_share_hyp(hyp_phys_to_pfn(rx));
+ if (ret) {
+ ret = FFA_RET_INVALID_PARAMETERS;
+ goto err_unshare_tx;
+ }
+
+ tx_virt = hyp_phys_to_virt(tx);
+ ret = hyp_pin_shared_mem(tx_virt, tx_virt + 1);
+ if (ret) {
+ ret = FFA_RET_INVALID_PARAMETERS;
+ goto err_unshare_rx;
+ }
+
+ rx_virt = hyp_phys_to_virt(rx);
+ ret = hyp_pin_shared_mem(rx_virt, rx_virt + 1);
+ if (ret) {
+ ret = FFA_RET_INVALID_PARAMETERS;
+ goto err_unpin_tx;
+ }
+
+ host_buffers.tx = tx_virt;
+ host_buffers.rx = rx_virt;
+
+out_unlock:
+ hyp_spin_unlock(&host_buffers.lock);
+out:
+ ffa_to_smccc_res(res, ret);
+ return;
+
+err_unpin_tx:
+ hyp_unpin_shared_mem(tx_virt, tx_virt + 1);
+err_unshare_rx:
+ __pkvm_host_unshare_hyp(hyp_phys_to_pfn(rx));
+err_unshare_tx:
+ __pkvm_host_unshare_hyp(hyp_phys_to_pfn(tx));
+err_unmap:
+ spmd_unmap_ffa_buffers();
+ goto out_unlock;
+}
+
+static void do_ffa_rxtx_unmap(struct arm_smccc_res *res,
+ struct kvm_cpu_context *ctxt)
+{
+ DECLARE_REG(u32, id, ctxt, 1);
+ int ret = 0;
+
+ if (id != HOST_FFA_ID) {
+ ret = FFA_RET_INVALID_PARAMETERS;
+ goto out;
+ }
+
+ hyp_spin_lock(&host_buffers.lock);
+ if (!host_buffers.tx) {
+ ret = FFA_RET_INVALID_PARAMETERS;
+ goto out_unlock;
+ }
+
+ hyp_unpin_shared_mem(host_buffers.tx, host_buffers.tx + 1);
+ WARN_ON(__pkvm_host_unshare_hyp(hyp_virt_to_pfn(host_buffers.tx)));
+ host_buffers.tx = NULL;
+
+ hyp_unpin_shared_mem(host_buffers.rx, host_buffers.rx + 1);
+ WARN_ON(__pkvm_host_unshare_hyp(hyp_virt_to_pfn(host_buffers.rx)));
+ host_buffers.rx = NULL;
+
+ spmd_unmap_ffa_buffers();
+
+out_unlock:
+ hyp_spin_unlock(&host_buffers.lock);
+out:
+ ffa_to_smccc_res(res, ret);
+}
+
/*
* Is a given FFA function supported, either by forwarding on directly
* or by handling at EL2?
@@ -119,10 +265,21 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
if (!is_ffa_call(func_id))
return false;

+ switch (func_id) {
+ /* Memory management */
+ case FFA_FN64_RXTX_MAP:
+ do_ffa_rxtx_map(&res, host_ctxt);
+ goto out_handled;
+ case FFA_RXTX_UNMAP:
+ do_ffa_rxtx_unmap(&res, host_ctxt);
+ goto out_handled;
+ }
+
if (ffa_call_supported(func_id))
return false; /* Pass through */

ffa_to_smccc_error(&res, FFA_RET_NOT_SUPPORTED);
+out_handled:
ffa_set_retval(host_ctxt, &res);
return true;
}
@@ -130,6 +287,7 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
int hyp_ffa_init(void *pages)
{
struct arm_smccc_res res;
+ size_t min_rxtx_sz;

if (kvm_host_psci_config.smccc_version < ARM_SMCCC_VERSION_1_2)
return 0;
@@ -148,11 +306,37 @@ int hyp_ffa_init(void *pages)
if (res.a2 != HOST_FFA_ID)
return -EINVAL;

+ arm_smccc_1_1_smc(FFA_FEATURES, FFA_FN64_RXTX_MAP,
+ 0, 0, 0, 0, 0, 0, &res);
+ if (res.a0 != FFA_SUCCESS)
+ return -EOPNOTSUPP;
+
+ switch (res.a2) {
+ case FFA_FEAT_RXTX_MIN_SZ_4K:
+ min_rxtx_sz = SZ_4K;
+ break;
+ case FFA_FEAT_RXTX_MIN_SZ_16K:
+ min_rxtx_sz = SZ_16K;
+ break;
+ case FFA_FEAT_RXTX_MIN_SZ_64K:
+ min_rxtx_sz = SZ_64K;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (min_rxtx_sz > PAGE_SIZE)
+ return -EOPNOTSUPP;
+
hyp_buffers = (struct kvm_ffa_buffers) {
.lock = __HYP_SPIN_LOCK_UNLOCKED,
.tx = pages,
.rx = pages + (KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE),
};

+ host_buffers = (struct kvm_ffa_buffers) {
+ .lock = __HYP_SPIN_LOCK_UNLOCKED,
+ };
+
return 0;
}
diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h
index c87aeecaa9b2..b9f81035eb41 100644
--- a/include/linux/arm_ffa.h
+++ b/include/linux/arm_ffa.h
@@ -94,6 +94,14 @@
*/
#define FFA_PAGE_SIZE SZ_4K

+/*
+ * Minimum buffer size/alignment encodings returned by an FFA_FEATURES
+ * query for FFA_RXTX_MAP.
+ */
+#define FFA_FEAT_RXTX_MIN_SZ_4K 0
+#define FFA_FEAT_RXTX_MIN_SZ_64K 1
+#define FFA_FEAT_RXTX_MIN_SZ_16K 2
+
/* FFA Bus/Device/Driver related */
struct ffa_device {
int vm_id;