[PATCH v2 00/10] KVM: arm64: FF-A proxy for pKVM

[PATCH v2 00/10] KVM: arm64: FF-A proxy for pKVM

[Will Deacon]

Hi folks,

This is the second version of the pKVM FF-A proxy patches that were
originally posted by Quentin a while back:

	https://lore.kernel.org/r/20221116170335.2341003-1-qperret@google.com

As described in the original cover letter, these patches provide a
mechanism for pKVM to intercept memory being shared between the host
and Trustzone in order to prevent "confused deputy" attacks where the
host can ask Trustzone to access protected guest pages.

Changes since v1 include:

  * Remove double negatives by inverting ffa_call_unsupported() into
    ffa_call_supported()

  * Re-order patch series so that FFA_FEATURES doesn't advertise
    unimplemented functions during bisection

  * Rework patches to introduce function switch case by case

  * Dropped the first two changes as they have been merged upstream

  * Dropped stray "ANDROID:" prefix from the final patch

Thanks to Oliver for his comments on the initial posting.

Patches based on -rc7 and also pushed here:

git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git kvm/ffa-proxy

Cheers,

Will

Cc: Quentin Perret <qperret@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: James Morse <james.morse@arm.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Sebastian Ene <sebastianene@google.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: kvmarm@lists.linux.dev
Cc: kernel-team@android.com

--->8	  

Fuad Tabba (1):
  KVM: arm64: Handle FFA_FEATURES call from the host

Quentin Perret (1):
  KVM: arm64: pkvm: Add support for fragmented FF-A descriptors

Will Deacon (8):
  KVM: arm64: Block unsafe FF-A calls from the host
  KVM: arm64: Probe FF-A version and host/hyp partition ID during init
  KVM: arm64: Allocate pages for hypervisor FF-A mailboxes
  KVM: arm64: Handle FFA_RXTX_MAP and FFA_RXTX_UNMAP calls from the host
  KVM: arm64: Add FF-A helpers to share/unshare memory with secure world
  KVM: arm64: Handle FFA_MEM_SHARE calls from the host
  KVM: arm64: Handle FFA_MEM_RECLAIM calls from the host
  KVM: arm64: Handle FFA_MEM_LEND calls from the host

 arch/arm64/include/asm/kvm_host.h             |   1 +
 arch/arm64/include/asm/kvm_pkvm.h             |  21 +
 arch/arm64/kvm/arm.c                          |   1 +
 arch/arm64/kvm/hyp/include/nvhe/ffa.h         |  17 +
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |   3 +
 arch/arm64/kvm/hyp/nvhe/Makefile              |   2 +-
 arch/arm64/kvm/hyp/nvhe/ffa.c                 | 745 ++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            |   3 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         |  68 ++
 arch/arm64/kvm/hyp/nvhe/setup.c               |  11 +
 arch/arm64/kvm/pkvm.c                         |   1 +
 include/linux/arm_ffa.h                       |   8 +
 12 files changed, 880 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/ffa.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/ffa.c

-- 
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[PATCH v2 01/10] KVM: arm64: Block unsafe FF-A calls from the host

[Will Deacon]

When KVM is initialised in protected mode, we must take care to filter
certain FFA calls from the host kernel so that the integrity of guest
and hypervisor memory is maintained and is not made available to the
secure world.

As a first step, intercept and block all memory-related FF-A SMC calls
from the host to EL3 and don't advertise any FF-A features. This puts
the framework in place for handling them properly.

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/include/nvhe/ffa.h |  16 ++++
 arch/arm64/kvm/hyp/nvhe/Makefile      |   2 +-
 arch/arm64/kvm/hyp/nvhe/ffa.c         | 106 ++++++++++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/hyp-main.c    |   3 +
 4 files changed, 126 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/kvm/hyp/include/nvhe/ffa.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/ffa.c

diff --git a/arch/arm64/kvm/hyp/include/nvhe/ffa.h b/arch/arm64/kvm/hyp/include/nvhe/ffa.h
new file mode 100644
index 000000000000..fc09ec671e24
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/ffa.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2022 - Google LLC
+ * Author: Andrew Walbran <qwandor@google.com>
+ */
+#ifndef __KVM_HYP_FFA_H
+#define __KVM_HYP_FFA_H
+
+#include <asm/kvm_host.h>
+
+#define FFA_MIN_FUNC_NUM 0x60
+#define FFA_MAX_FUNC_NUM 0x7F
+
+bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt);
+
+#endif /* __KVM_HYP_FFA_H */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 530347cdebe3..9ddc025e4b86 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -22,7 +22,7 @@ lib-objs := $(addprefix ../../../lib/, $(lib-objs))
 
 hyp-obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
 	 hyp-main.o hyp-smp.o psci-relay.o early_alloc.o page_alloc.o \
-	 cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o stacktrace.o
+	 cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o stacktrace.o ffa.o
 hyp-obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
 hyp-obj-$(CONFIG_DEBUG_LIST) += list_debug.o
diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
new file mode 100644
index 000000000000..a437b0727881
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * FF-A v1.0 proxy to filter out invalid memory-sharing SMC calls issued by
+ * the host. FF-A is a slightly more palatable abbreviation of "Arm Firmware
+ * Framework for Arm A-profile", which is specified by Arm in document
+ * number DEN0077.
+ *
+ * Copyright (C) 2022 - Google LLC
+ * Author: Andrew Walbran <qwandor@google.com>
+ *
+ * This driver hooks into the SMC trapping logic for the host and intercepts
+ * all calls falling within the FF-A range. Each call is either:
+ *
+ *	- Forwarded on unmodified to the SPMD at EL3
+ *	- Rejected as "unsupported"
+ *	- Accompanied by a host stage-2 page-table check/update and reissued
+ *
+ * Consequently, any attempts by the host to make guest memory pages
+ * accessible to the secure world using FF-A will be detected either here
+ * (in the case that the memory is already owned by the guest) or during
+ * donation to the guest (in the case that the memory was previously shared
+ * with the secure world).
+ *
+ * To allow the rolling-back of page-table updates and FF-A calls in the
+ * event of failure, operations involving the RXTX buffers are locked for
+ * the duration and are therefore serialised.
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/arm_ffa.h>
+#include <nvhe/ffa.h>
+#include <nvhe/trap_handler.h>
+
+static void ffa_to_smccc_error(struct arm_smccc_res *res, u64 ffa_errno)
+{
+	*res = (struct arm_smccc_res) {
+		.a0	= FFA_ERROR,
+		.a2	= ffa_errno,
+	};
+}
+
+static void ffa_set_retval(struct kvm_cpu_context *ctxt,
+			   struct arm_smccc_res *res)
+{
+	cpu_reg(ctxt, 0) = res->a0;
+	cpu_reg(ctxt, 1) = res->a1;
+	cpu_reg(ctxt, 2) = res->a2;
+	cpu_reg(ctxt, 3) = res->a3;
+}
+
+static bool is_ffa_call(u64 func_id)
+{
+	return ARM_SMCCC_IS_FAST_CALL(func_id) &&
+	       ARM_SMCCC_OWNER_NUM(func_id) == ARM_SMCCC_OWNER_STANDARD &&
+	       ARM_SMCCC_FUNC_NUM(func_id) >= FFA_MIN_FUNC_NUM &&
+	       ARM_SMCCC_FUNC_NUM(func_id) <= FFA_MAX_FUNC_NUM;
+}
+
+/*
+ * Is a given FFA function supported, either by forwarding on directly
+ * or by handling at EL2?
+ */
+static bool ffa_call_supported(u64 func_id)
+{
+	switch (func_id) {
+	/* Unsupported memory management calls */
+	case FFA_FN64_MEM_RETRIEVE_REQ:
+	case FFA_MEM_RETRIEVE_RESP:
+	case FFA_MEM_RELINQUISH:
+	case FFA_MEM_OP_PAUSE:
+	case FFA_MEM_OP_RESUME:
+	case FFA_MEM_FRAG_RX:
+	case FFA_FN64_MEM_DONATE:
+	/* Indirect message passing via RX/TX buffers */
+	case FFA_MSG_SEND:
+	case FFA_MSG_POLL:
+	case FFA_MSG_WAIT:
+	/* 32-bit variants of 64-bit calls */
+	case FFA_MSG_SEND_DIRECT_REQ:
+	case FFA_MSG_SEND_DIRECT_RESP:
+	case FFA_RXTX_MAP:
+	case FFA_MEM_DONATE:
+	case FFA_MEM_RETRIEVE_REQ:
+	/* Don't advertise any features just yet */
+	case FFA_FEATURES:
+		return false;
+	}
+
+	return true;
+}
+
+bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(u64, func_id, host_ctxt, 0);
+	struct arm_smccc_res res;
+
+	if (!is_ffa_call(func_id))
+		return false;
+
+	if (ffa_call_supported(func_id))
+		return false; /* Pass through */
+
+	ffa_to_smccc_error(&res, FFA_RET_NOT_SUPPORTED);
+	ffa_set_retval(host_ctxt, &res);
+	return true;
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 728e01d4536b..223611e43279 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -13,6 +13,7 @@
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 
+#include <nvhe/ffa.h>
 #include <nvhe/mem_protect.h>
 #include <nvhe/mm.h>
 #include <nvhe/pkvm.h>
@@ -373,6 +374,8 @@ static void handle_host_smc(struct kvm_cpu_context *host_ctxt)
 	bool handled;
 
 	handled = kvm_host_psci_handler(host_ctxt);
+	if (!handled)
+		handled = kvm_host_ffa_handler(host_ctxt);
 	if (!handled)
 		default_host_smc_handler(host_ctxt);
 
-- 
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[PATCH v2 02/10] KVM: arm64: Probe FF-A version and host/hyp partition ID during init

[Will Deacon]

Probe FF-A during pKVM initialisation so that we can detect any
inconsistencies in the version or partition ID early on.

Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/kvm_host.h     |  1 +
 arch/arm64/kvm/arm.c                  |  1 +
 arch/arm64/kvm/hyp/include/nvhe/ffa.h |  1 +
 arch/arm64/kvm/hyp/nvhe/ffa.c         | 30 +++++++++++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/setup.c       |  5 +++++
 5 files changed, 38 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index bcd774d74f34..b7fe6e829231 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -391,6 +391,7 @@ struct kvm_host_data {
 struct kvm_host_psci_config {
 	/* PSCI version used by host. */
 	u32 version;
+	u32 smccc_version;
 
 	/* Function IDs used by host if version is v0.1. */
 	struct psci_0_1_function_ids function_ids_0_1;
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 4b2e16e696a8..3dab9a33e9f8 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1790,6 +1790,7 @@ static bool __init init_psci_relay(void)
 	}
 
 	kvm_host_psci_config.version = psci_ops.get_version();
+	kvm_host_psci_config.smccc_version = arm_smccc_get_version();
 
 	if (kvm_host_psci_config.version == PSCI_VERSION(0, 1)) {
 		kvm_host_psci_config.function_ids_0_1 = get_psci_0_1_function_ids();
diff --git a/arch/arm64/kvm/hyp/include/nvhe/ffa.h b/arch/arm64/kvm/hyp/include/nvhe/ffa.h
index fc09ec671e24..5c9b92430ff3 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/ffa.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/ffa.h
@@ -11,6 +11,7 @@
 #define FFA_MIN_FUNC_NUM 0x60
 #define FFA_MAX_FUNC_NUM 0x7F
 
+int hyp_ffa_init(void);
 bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt);
 
 #endif /* __KVM_HYP_FFA_H */
diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index a437b0727881..b387e433f15e 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -31,6 +31,12 @@
 #include <nvhe/ffa.h>
 #include <nvhe/trap_handler.h>
 
+/*
+ * "ID value 0 must be returned at the Non-secure physical FF-A instance"
+ * We share this ID with the host.
+ */
+#define HOST_FFA_ID	0
+
 static void ffa_to_smccc_error(struct arm_smccc_res *res, u64 ffa_errno)
 {
 	*res = (struct arm_smccc_res) {
@@ -104,3 +110,27 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
 	ffa_set_retval(host_ctxt, &res);
 	return true;
 }
+
+int hyp_ffa_init(void)
+{
+	struct arm_smccc_res res;
+
+	if (kvm_host_psci_config.smccc_version < ARM_SMCCC_VERSION_1_2)
+		return 0;
+
+	arm_smccc_1_1_smc(FFA_VERSION, FFA_VERSION_1_0, 0, 0, 0, 0, 0, 0, &res);
+	if (res.a0 == FFA_RET_NOT_SUPPORTED)
+		return 0;
+
+	if (res.a0 != FFA_VERSION_1_0)
+		return -EOPNOTSUPP;
+
+	arm_smccc_1_1_smc(FFA_ID_GET, 0, 0, 0, 0, 0, 0, 0, &res);
+	if (res.a0 != FFA_SUCCESS)
+		return -EOPNOTSUPP;
+
+	if (res.a2 != HOST_FFA_ID)
+		return -EINVAL;
+
+	return 0;
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 110f04627785..c4ca174a0592 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -11,6 +11,7 @@
 #include <asm/kvm_pkvm.h>
 
 #include <nvhe/early_alloc.h>
+#include <nvhe/ffa.h>
 #include <nvhe/fixed_config.h>
 #include <nvhe/gfp.h>
 #include <nvhe/memory.h>
@@ -314,6 +315,10 @@ void __noreturn __pkvm_init_finalise(void)
 	if (ret)
 		goto out;
 
+	ret = hyp_ffa_init();
+	if (ret)
+		goto out;
+
 	pkvm_hyp_vm_table_init(vm_table_base);
 out:
 	/*
-- 
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[PATCH v2 03/10] KVM: arm64: Allocate pages for hypervisor FF-A mailboxes

[Will Deacon]

The FF-A proxy code needs to allocate its own buffer pair for
communication with EL3 and for forwarding calls from the host at EL1.

Reserve a couple of pages for this purpose and use them to initialise
the hypervisor's FF-A buffer structure.

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/include/asm/kvm_pkvm.h     |  8 ++++++++
 arch/arm64/kvm/hyp/include/nvhe/ffa.h |  2 +-
 arch/arm64/kvm/hyp/nvhe/ffa.c         | 24 +++++++++++++++++++++++-
 arch/arm64/kvm/hyp/nvhe/setup.c       |  8 +++++++-
 arch/arm64/kvm/pkvm.c                 |  1 +
 5 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index 01129b0d4c68..2b495ec59deb 100644
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -106,4 +106,12 @@ static inline unsigned long host_s2_pgtable_pages(void)
 	return res;
 }
 
+#define KVM_FFA_MBOX_NR_PAGES	1
+
+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;
+}
+
 #endif	/* __ARM64_KVM_PKVM_H__ */
diff --git a/arch/arm64/kvm/hyp/include/nvhe/ffa.h b/arch/arm64/kvm/hyp/include/nvhe/ffa.h
index 5c9b92430ff3..1becb10ecd80 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/ffa.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/ffa.h
@@ -11,7 +11,7 @@
 #define FFA_MIN_FUNC_NUM 0x60
 #define FFA_MAX_FUNC_NUM 0x7F
 
-int hyp_ffa_init(void);
+int hyp_ffa_init(void *pages);
 bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt);
 
 #endif /* __KVM_HYP_FFA_H */
diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index b387e433f15e..de0fba79b195 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -28,8 +28,11 @@
 
 #include <linux/arm-smccc.h>
 #include <linux/arm_ffa.h>
+#include <asm/kvm_pkvm.h>
+
 #include <nvhe/ffa.h>
 #include <nvhe/trap_handler.h>
+#include <nvhe/spinlock.h>
 
 /*
  * "ID value 0 must be returned at the Non-secure physical FF-A instance"
@@ -37,6 +40,19 @@
  */
 #define HOST_FFA_ID	0
 
+struct kvm_ffa_buffers {
+	hyp_spinlock_t lock;
+	void *tx;
+	void *rx;
+};
+
+/*
+ * Note that we don't currently lock these buffers explicitly, instead
+ * relying on the locking of the host FFA buffers as we only have one
+ * client.
+ */
+static struct kvm_ffa_buffers hyp_buffers;
+
 static void ffa_to_smccc_error(struct arm_smccc_res *res, u64 ffa_errno)
 {
 	*res = (struct arm_smccc_res) {
@@ -111,7 +127,7 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
 	return true;
 }
 
-int hyp_ffa_init(void)
+int hyp_ffa_init(void *pages)
 {
 	struct arm_smccc_res res;
 
@@ -132,5 +148,11 @@ int hyp_ffa_init(void)
 	if (res.a2 != HOST_FFA_ID)
 		return -EINVAL;
 
+	hyp_buffers = (struct kvm_ffa_buffers) {
+		.lock	= __HYP_SPIN_LOCK_UNLOCKED,
+		.tx	= pages,
+		.rx	= pages + (KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE),
+	};
+
 	return 0;
 }
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index c4ca174a0592..bb98630dfeaf 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -29,6 +29,7 @@ static void *vmemmap_base;
 static void *vm_table_base;
 static void *hyp_pgt_base;
 static void *host_s2_pgt_base;
+static void *ffa_proxy_pages;
 static struct kvm_pgtable_mm_ops pkvm_pgtable_mm_ops;
 static struct hyp_pool hpool;
 
@@ -58,6 +59,11 @@ static int divide_memory_pool(void *virt, unsigned long size)
 	if (!host_s2_pgt_base)
 		return -ENOMEM;
 
+	nr_pages = hyp_ffa_proxy_pages();
+	ffa_proxy_pages = hyp_early_alloc_contig(nr_pages);
+	if (!ffa_proxy_pages)
+		return -ENOMEM;
+
 	return 0;
 }
 
@@ -315,7 +321,7 @@ void __noreturn __pkvm_init_finalise(void)
 	if (ret)
 		goto out;
 
-	ret = hyp_ffa_init();
+	ret = hyp_ffa_init(ffa_proxy_pages);
 	if (ret)
 		goto out;
 
diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
index cf56958b1492..bb405e274df6 100644
--- a/arch/arm64/kvm/pkvm.c
+++ b/arch/arm64/kvm/pkvm.c
@@ -74,6 +74,7 @@ void __init kvm_hyp_reserve(void)
 	hyp_mem_pages += host_s2_pgtable_pages();
 	hyp_mem_pages += hyp_vm_table_pages();
 	hyp_mem_pages += hyp_vmemmap_pages(STRUCT_HYP_PAGE_SIZE);
+	hyp_mem_pages += hyp_ffa_proxy_pages();
 
 	/*
 	 * Try to allocate a PMD-aligned region to reduce TLB pressure once
-- 
2.40.0.634.g4ca3ef3211-goog


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

[Will Deacon]

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;
-- 
2.40.0.634.g4ca3ef3211-goog


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v2 05/10] KVM: arm64: Add FF-A helpers to share/unshare memory with secure world

[Will Deacon]

Extend pKVM's memory protection code so that we can update the host's
stage-2 page-table to track pages shared with secure world by the host
using FF-A and prevent those pages from being mapped into a guest.

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/include/nvhe/mem_protect.h |  3 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 68 +++++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index b7bdbe63deed..0972faccc2af 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -57,6 +57,7 @@ extern struct host_mmu host_mmu;
 enum pkvm_component_id {
 	PKVM_ID_HOST,
 	PKVM_ID_HYP,
+	PKVM_ID_FFA,
 };
 
 extern unsigned long hyp_nr_cpus;
@@ -66,6 +67,8 @@ int __pkvm_host_share_hyp(u64 pfn);
 int __pkvm_host_unshare_hyp(u64 pfn);
 int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages);
 int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
+int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages);
+int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);
 
 bool addr_is_memory(phys_addr_t phys);
 int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot);
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 552653fa18be..e721fba3bb33 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -835,6 +835,13 @@ static int check_share(struct pkvm_mem_share *share)
 	case PKVM_ID_HYP:
 		ret = hyp_ack_share(completer_addr, tx, share->completer_prot);
 		break;
+	case PKVM_ID_FFA:
+		/*
+		 * We only check the host; the secure side will check the other
+		 * end when we forward the FFA call.
+		 */
+		ret = 0;
+		break;
 	default:
 		ret = -EINVAL;
 	}
@@ -863,6 +870,13 @@ static int __do_share(struct pkvm_mem_share *share)
 	case PKVM_ID_HYP:
 		ret = hyp_complete_share(completer_addr, tx, share->completer_prot);
 		break;
+	case PKVM_ID_FFA:
+		/*
+		 * We're not responsible for any secure page-tables, so there's
+		 * nothing to do here.
+		 */
+		ret = 0;
+		break;
 	default:
 		ret = -EINVAL;
 	}
@@ -911,6 +925,10 @@ static int check_unshare(struct pkvm_mem_share *share)
 	case PKVM_ID_HYP:
 		ret = hyp_ack_unshare(completer_addr, tx);
 		break;
+	case PKVM_ID_FFA:
+		/* See check_share() */
+		ret = 0;
+		break;
 	default:
 		ret = -EINVAL;
 	}
@@ -939,6 +957,10 @@ static int __do_unshare(struct pkvm_mem_share *share)
 	case PKVM_ID_HYP:
 		ret = hyp_complete_unshare(completer_addr, tx);
 		break;
+	case PKVM_ID_FFA:
+		/* See __do_share() */
+		ret = 0;
+		break;
 	default:
 		ret = -EINVAL;
 	}
@@ -1228,3 +1250,49 @@ void hyp_unpin_shared_mem(void *from, void *to)
 	hyp_unlock_component();
 	host_unlock_component();
 }
+
+int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages)
+{
+	int ret;
+	struct pkvm_mem_share share = {
+		.tx	= {
+			.nr_pages	= nr_pages,
+			.initiator	= {
+				.id	= PKVM_ID_HOST,
+				.addr	= hyp_pfn_to_phys(pfn),
+			},
+			.completer	= {
+				.id	= PKVM_ID_FFA,
+			},
+		},
+	};
+
+	host_lock_component();
+	ret = do_share(&share);
+	host_unlock_component();
+
+	return ret;
+}
+
+int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages)
+{
+	int ret;
+	struct pkvm_mem_share share = {
+		.tx	= {
+			.nr_pages	= nr_pages,
+			.initiator	= {
+				.id	= PKVM_ID_HOST,
+				.addr	= hyp_pfn_to_phys(pfn),
+			},
+			.completer	= {
+				.id	= PKVM_ID_FFA,
+			},
+		},
+	};
+
+	host_lock_component();
+	ret = do_unshare(&share);
+	host_unlock_component();
+
+	return ret;
+}
-- 
2.40.0.634.g4ca3ef3211-goog


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v2 06/10] KVM: arm64: Handle FFA_MEM_SHARE calls from the host

[Will Deacon]

Intercept FFA_MEM_SHARE/FFA_FN64_MEM_SHARE calls from the host and
transition the host stage-2 page-table entries from the OWNED state to
the SHARED_OWNED state prior to forwarding the call onto 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 | 155 ++++++++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 9ee3be517e1e..95bc70e52e91 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -116,6 +116,14 @@ static int spmd_unmap_ffa_buffers(void)
 	return res.a0 == FFA_SUCCESS ? FFA_RET_SUCCESS : res.a2;
 }
 
+static void spmd_mem_share(struct arm_smccc_res *res, u32 len, u32 fraglen)
+{
+	arm_smccc_1_1_smc(FFA_FN64_MEM_SHARE,
+			  len, fraglen,
+			  0, 0, 0, 0, 0,
+			  res);
+}
+
 static void do_ffa_rxtx_map(struct arm_smccc_res *res,
 			    struct kvm_cpu_context *ctxt)
 {
@@ -224,6 +232,149 @@ static void do_ffa_rxtx_unmap(struct arm_smccc_res *res,
 	ffa_to_smccc_res(res, ret);
 }
 
+static u32 __ffa_host_share_ranges(struct ffa_mem_region_addr_range *ranges,
+				   u32 nranges)
+{
+	u32 i;
+
+	for (i = 0; i < nranges; ++i) {
+		struct ffa_mem_region_addr_range *range = &ranges[i];
+		u64 sz = (u64)range->pg_cnt * FFA_PAGE_SIZE;
+		u64 pfn = hyp_phys_to_pfn(range->address);
+
+		if (!PAGE_ALIGNED(sz))
+			break;
+
+		if (__pkvm_host_share_ffa(pfn, sz / PAGE_SIZE))
+			break;
+	}
+
+	return i;
+}
+
+static u32 __ffa_host_unshare_ranges(struct ffa_mem_region_addr_range *ranges,
+				     u32 nranges)
+{
+	u32 i;
+
+	for (i = 0; i < nranges; ++i) {
+		struct ffa_mem_region_addr_range *range = &ranges[i];
+		u64 sz = (u64)range->pg_cnt * FFA_PAGE_SIZE;
+		u64 pfn = hyp_phys_to_pfn(range->address);
+
+		if (!PAGE_ALIGNED(sz))
+			break;
+
+		if (__pkvm_host_unshare_ffa(pfn, sz / PAGE_SIZE))
+			break;
+	}
+
+	return i;
+}
+
+static int ffa_host_share_ranges(struct ffa_mem_region_addr_range *ranges,
+				 u32 nranges)
+{
+	u32 nshared = __ffa_host_share_ranges(ranges, nranges);
+	int ret = 0;
+
+	if (nshared != nranges) {
+		WARN_ON(__ffa_host_unshare_ranges(ranges, nshared) != nshared);
+		ret = FFA_RET_DENIED;
+	}
+
+	return ret;
+}
+
+static int ffa_host_unshare_ranges(struct ffa_mem_region_addr_range *ranges,
+				   u32 nranges)
+{
+	u32 nunshared = __ffa_host_unshare_ranges(ranges, nranges);
+	int ret = 0;
+
+	if (nunshared != nranges) {
+		WARN_ON(__ffa_host_share_ranges(ranges, nunshared) != nunshared);
+		ret = FFA_RET_DENIED;
+	}
+
+	return ret;
+}
+
+static void do_ffa_mem_share(struct arm_smccc_res *res,
+			     struct kvm_cpu_context *ctxt)
+{
+	DECLARE_REG(u32, len, ctxt, 1);
+	DECLARE_REG(u32, fraglen, ctxt, 2);
+	DECLARE_REG(u64, addr_mbz, ctxt, 3);
+	DECLARE_REG(u32, npages_mbz, ctxt, 4);
+	struct ffa_composite_mem_region *reg;
+	struct ffa_mem_region *buf;
+	int ret = 0;
+	u32 offset;
+
+	if (addr_mbz || npages_mbz || fraglen > len ||
+	    fraglen > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) {
+		ret = FFA_RET_INVALID_PARAMETERS;
+		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;
+		goto out;
+	}
+
+	hyp_spin_lock(&host_buffers.lock);
+	if (!host_buffers.tx) {
+		ret = FFA_RET_INVALID_PARAMETERS;
+		goto out_unlock;
+	}
+
+	buf = hyp_buffers.tx;
+	memcpy(buf, host_buffers.tx, fraglen);
+
+	offset = buf->ep_mem_access[0].composite_off;
+	if (!offset || buf->ep_count != 1 || buf->sender_id != HOST_FFA_ID) {
+		ret = FFA_RET_INVALID_PARAMETERS;
+		goto out_unlock;
+	}
+
+	if (fraglen < offset + sizeof(struct ffa_composite_mem_region)) {
+		ret = FFA_RET_INVALID_PARAMETERS;
+		goto out_unlock;
+	}
+
+	reg = (void *)buf + offset;
+	if (fraglen < offset + sizeof(struct ffa_composite_mem_region) +
+		      reg->addr_range_cnt *
+		      sizeof(struct ffa_mem_region_addr_range)) {
+		ret = FFA_RET_INVALID_PARAMETERS;
+		goto out_unlock;
+	}
+
+	ret = ffa_host_share_ranges(reg->constituents, reg->addr_range_cnt);
+	if (ret)
+		goto out_unlock;
+
+	spmd_mem_share(res, len, fraglen);
+	if (res->a0 != FFA_SUCCESS) {
+		WARN_ON(ffa_host_unshare_ranges(reg->constituents,
+						reg->addr_range_cnt));
+	}
+
+out_unlock:
+	hyp_spin_unlock(&host_buffers.lock);
+out:
+	if (ret)
+		ffa_to_smccc_res(res, ret);
+	return;
+}
+
 /*
  * Is a given FFA function supported, either by forwarding on directly
  * or by handling at EL2?
@@ -273,6 +424,10 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
 	case FFA_RXTX_UNMAP:
 		do_ffa_rxtx_unmap(&res, host_ctxt);
 		goto out_handled;
+	case FFA_MEM_SHARE:
+	case FFA_FN64_MEM_SHARE:
+		do_ffa_mem_share(&res, host_ctxt);
+		goto out_handled;
 	}
 
 	if (ffa_call_supported(func_id))
-- 
2.40.0.634.g4ca3ef3211-goog


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[PATCH v2 07/10] KVM: arm64: Handle FFA_MEM_RECLAIM calls from the host

[Will Deacon]

Intecept FFA_MEM_RECLAIM calls from the host and transition the host
stage-2 page-table entries from the SHARED_OWNED state back to the OWNED
state once EL3 has confirmed that the secure mapping has been reclaimed.

Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 79 +++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 95bc70e52e91..b23e3869ce63 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -124,6 +124,23 @@ static void spmd_mem_share(struct arm_smccc_res *res, u32 len, u32 fraglen)
 			  res);
 }
 
+static void spmd_mem_reclaim(struct arm_smccc_res *res, u32 handle_lo,
+			     u32 handle_hi, u32 flags)
+{
+	arm_smccc_1_1_smc(FFA_MEM_RECLAIM,
+			  handle_lo, handle_hi, flags,
+			  0, 0, 0, 0,
+			  res);
+}
+
+static void spmd_retrieve_req(struct arm_smccc_res *res, u32 len)
+{
+	arm_smccc_1_1_smc(FFA_FN64_MEM_RETRIEVE_REQ,
+			  len, len,
+			  0, 0, 0, 0, 0,
+			  res);
+}
+
 static void do_ffa_rxtx_map(struct arm_smccc_res *res,
 			    struct kvm_cpu_context *ctxt)
 {
@@ -375,6 +392,65 @@ static void do_ffa_mem_share(struct arm_smccc_res *res,
 	return;
 }
 
+static void do_ffa_mem_reclaim(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, flags, ctxt, 3);
+	struct ffa_composite_mem_region *reg;
+	struct ffa_mem_region *buf;
+	int ret = 0;
+	u32 offset;
+	u64 handle;
+
+	handle = PACK_HANDLE(handle_lo, handle_hi);
+
+	hyp_spin_lock(&host_buffers.lock);
+
+	buf = hyp_buffers.tx;
+	*buf = (struct ffa_mem_region) {
+		.sender_id	= HOST_FFA_ID,
+		.handle		= handle,
+	};
+
+	spmd_retrieve_req(res, sizeof(*buf));
+	buf = hyp_buffers.rx;
+	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;
+	}
+
+	offset = buf->ep_mem_access[0].composite_off;
+	/*
+	 * We can trust the SPMD to get this right, but let's at least
+	 * check that we end up with something that doesn't look _completely_
+	 * bogus.
+	 */
+	if (WARN_ON(offset > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE)) {
+		ret = FFA_RET_ABORTED;
+		goto out_unlock;
+	}
+
+	reg = (void *)buf + offset;
+	spmd_mem_reclaim(res, handle_lo, handle_hi, flags);
+	if (res->a0 != FFA_SUCCESS)
+		goto out_unlock;
+
+	/* If the SPMD was happy, then we should be too. */
+	WARN_ON(ffa_host_unshare_ranges(reg->constituents,
+					reg->addr_range_cnt));
+out_unlock:
+	hyp_spin_unlock(&host_buffers.lock);
+
+	if (ret)
+		ffa_to_smccc_res(res, ret);
+}
+
 /*
  * Is a given FFA function supported, either by forwarding on directly
  * or by handling at EL2?
@@ -428,6 +504,9 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
 	case FFA_FN64_MEM_SHARE:
 		do_ffa_mem_share(&res, host_ctxt);
 		goto out_handled;
+	case FFA_MEM_RECLAIM:
+		do_ffa_mem_reclaim(&res, host_ctxt);
+		goto out_handled;
 	}
 
 	if (ffa_call_supported(func_id))
-- 
2.40.0.634.g4ca3ef3211-goog


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[PATCH v2 08/10] KVM: arm64: Handle FFA_MEM_LEND calls from the host

[Will Deacon]

Handle FFA_MEM_LEND calls from the host by treating them identically to
FFA_MEM_SHARE calls for the purposes of the host stage-2 page-table, but
forwarding on the original request to EL3.

Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index b23e3869ce63..45a2726d73ff 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -116,10 +116,10 @@ static int spmd_unmap_ffa_buffers(void)
 	return res.a0 == FFA_SUCCESS ? FFA_RET_SUCCESS : res.a2;
 }
 
-static void spmd_mem_share(struct arm_smccc_res *res, u32 len, u32 fraglen)
+static void spmd_mem_xfer(struct arm_smccc_res *res, u64 func_id, u32 len,
+			  u32 fraglen)
 {
-	arm_smccc_1_1_smc(FFA_FN64_MEM_SHARE,
-			  len, fraglen,
+	arm_smccc_1_1_smc(func_id, len, fraglen,
 			  0, 0, 0, 0, 0,
 			  res);
 }
@@ -317,8 +317,9 @@ static int ffa_host_unshare_ranges(struct ffa_mem_region_addr_range *ranges,
 	return ret;
 }
 
-static void do_ffa_mem_share(struct arm_smccc_res *res,
-			     struct kvm_cpu_context *ctxt)
+static __always_inline 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);
@@ -329,6 +330,9 @@ static void do_ffa_mem_share(struct arm_smccc_res *res,
 	int ret = 0;
 	u32 offset;
 
+	BUILD_BUG_ON(func_id != FFA_FN64_MEM_SHARE &&
+		     func_id != FFA_FN64_MEM_LEND);
+
 	if (addr_mbz || npages_mbz || fraglen > len ||
 	    fraglen > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) {
 		ret = FFA_RET_INVALID_PARAMETERS;
@@ -378,7 +382,7 @@ static void do_ffa_mem_share(struct arm_smccc_res *res,
 	if (ret)
 		goto out_unlock;
 
-	spmd_mem_share(res, len, fraglen);
+	spmd_mem_xfer(res, func_id, len, fraglen);
 	if (res->a0 != FFA_SUCCESS) {
 		WARN_ON(ffa_host_unshare_ranges(reg->constituents,
 						reg->addr_range_cnt));
@@ -502,11 +506,15 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
 		goto out_handled;
 	case FFA_MEM_SHARE:
 	case FFA_FN64_MEM_SHARE:
-		do_ffa_mem_share(&res, host_ctxt);
+		do_ffa_mem_xfer(FFA_FN64_MEM_SHARE, &res, host_ctxt);
 		goto out_handled;
 	case FFA_MEM_RECLAIM:
 		do_ffa_mem_reclaim(&res, host_ctxt);
 		goto out_handled;
+	case FFA_MEM_LEND:
+	case FFA_FN64_MEM_LEND:
+		do_ffa_mem_xfer(FFA_FN64_MEM_LEND, &res, host_ctxt);
+		goto out_handled;
 	}
 
 	if (ffa_call_supported(func_id))
-- 
2.40.0.634.g4ca3ef3211-goog


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[PATCH v2 09/10] KVM: arm64: Handle FFA_FEATURES call from the host

[Will Deacon]

From: Fuad Tabba <tabba@google.com>

Filter out advertising unsupported features, and only advertise
features and properties that are supported by the hypervisor proxy.

Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 45 +++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 45a2726d73ff..aa8bfc97a164 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -64,15 +64,21 @@ 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)
+static void ffa_to_smccc_res_prop(struct arm_smccc_res *res, int ret, u64 prop)
 {
 	if (ret == FFA_RET_SUCCESS) {
-		*res = (struct arm_smccc_res) { .a0 = FFA_SUCCESS };
+		*res = (struct arm_smccc_res) { .a0 = FFA_SUCCESS,
+						.a2 = prop };
 	} else {
 		ffa_to_smccc_error(res, ret);
 	}
 }
 
+static void ffa_to_smccc_res(struct arm_smccc_res *res, int ret)
+{
+	ffa_to_smccc_res_prop(res, ret, 0);
+}
+
 static void ffa_set_retval(struct kvm_cpu_context *ctxt,
 			   struct arm_smccc_res *res)
 {
@@ -480,14 +486,41 @@ static bool ffa_call_supported(u64 func_id)
 	case FFA_RXTX_MAP:
 	case FFA_MEM_DONATE:
 	case FFA_MEM_RETRIEVE_REQ:
-	/* Don't advertise any features just yet */
-	case FFA_FEATURES:
 		return false;
 	}
 
 	return true;
 }
 
+static bool do_ffa_features(struct arm_smccc_res *res,
+			    struct kvm_cpu_context *ctxt)
+{
+	DECLARE_REG(u32, id, ctxt, 1);
+	u64 prop = 0;
+	int ret = 0;
+
+	if (!ffa_call_supported(id)) {
+		ret = FFA_RET_NOT_SUPPORTED;
+		goto out_handled;
+	}
+
+	switch (id) {
+	case FFA_MEM_SHARE:
+	case FFA_FN64_MEM_SHARE:
+	case FFA_MEM_LEND:
+	case FFA_FN64_MEM_LEND:
+		ret = FFA_RET_SUCCESS;
+		prop = 0; /* No support for dynamic buffers */
+		goto out_handled;
+	default:
+		return false;
+	}
+
+out_handled:
+	ffa_to_smccc_res_prop(res, ret, prop);
+	return true;
+}
+
 bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
 {
 	DECLARE_REG(u64, func_id, host_ctxt, 0);
@@ -497,6 +530,10 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
 		return false;
 
 	switch (func_id) {
+	case FFA_FEATURES:
+		if (!do_ffa_features(&res, host_ctxt))
+			return false;
+		goto out_handled;
 	/* Memory management */
 	case FFA_FN64_RXTX_MAP:
 		do_ffa_rxtx_map(&res, host_ctxt);
-- 
2.40.0.634.g4ca3ef3211-goog


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[PATCH v2 10/10] KVM: arm64: pkvm: Add support for fragmented FF-A descriptors

[Will Deacon]

From: Quentin Perret <qperret@google.com>

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 <qwandor@google.com>
Signed-off-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 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 2b495ec59deb..e46250a02017 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 <linux/arm_ffa.h>
 #include <linux/memblock.h>
+#include <linux/scatterlist.h>
 #include <asm/kvm_pgtable.h>
 
 /* 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 aa8bfc97a164..a787f9134c39 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 spmd_unmap_ffa_buffers(void)
 	return res.a0 == FFA_SUCCESS ? FFA_RET_SUCCESS : res.a2;
 }
 
+static void spmd_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 spmd_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 spmd_mem_xfer(struct arm_smccc_res *res, u64 func_id, u32 len,
 			  u32 fraglen)
 {
@@ -323,6 +353,64 @@ 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.
+		 */
+		spmd_mem_reclaim(res, handle_lo, handle_hi, 0);
+		WARN_ON(res->a0 != FFA_SUCCESS);
+		goto out_unlock;
+	}
+
+	spmd_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)
@@ -333,8 +421,8 @@ 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);
@@ -345,11 +433,6 @@ 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;
@@ -377,21 +460,26 @@ 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;
 
 	spmd_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:
@@ -400,6 +488,10 @@ static __always_inline void do_ffa_mem_xfer(const u64 func_id,
 	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,
@@ -409,9 +501,9 @@ 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);
@@ -429,11 +521,8 @@ 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;
 	/*
@@ -441,16 +530,36 @@ 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) {
+		spmd_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);
+	}
+
 	spmd_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));
@@ -552,6 +661,9 @@ 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))
@@ -567,6 +679,7 @@ 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;
@@ -607,10 +720,21 @@ 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) {
-- 
2.40.0.634.g4ca3ef3211-goog


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Re: [PATCH v2 01/10] KVM: arm64: Block unsafe FF-A calls from the host

[Will Deacon]

Hi Oliver,

On Wed, May 10, 2023 at 07:08:01PM +0000, Oliver Upton wrote:
> On Wed, Apr 19, 2023 at 01:20:42PM +0100, Will Deacon wrote:
> > +/*
> > + * Is a given FFA function supported, either by forwarding on directly
> > + * or by handling at EL2?
> > + */
> > +static bool ffa_call_supported(u64 func_id)
> > +{
> > +	switch (func_id) {
> > +	/* Unsupported memory management calls */
> > +	case FFA_FN64_MEM_RETRIEVE_REQ:
> > +	case FFA_MEM_RETRIEVE_RESP:
> > +	case FFA_MEM_RELINQUISH:
> > +	case FFA_MEM_OP_PAUSE:
> > +	case FFA_MEM_OP_RESUME:
> > +	case FFA_MEM_FRAG_RX:
> > +	case FFA_FN64_MEM_DONATE:
> > +	/* Indirect message passing via RX/TX buffers */
> > +	case FFA_MSG_SEND:
> > +	case FFA_MSG_POLL:
> > +	case FFA_MSG_WAIT:
> > +	/* 32-bit variants of 64-bit calls */
> > +	case FFA_MSG_SEND_DIRECT_REQ:
> > +	case FFA_MSG_SEND_DIRECT_RESP:
> > +	case FFA_RXTX_MAP:
> > +	case FFA_MEM_DONATE:
> > +	case FFA_MEM_RETRIEVE_REQ:
> > +	/* Don't advertise any features just yet */
> > +	case FFA_FEATURES:
> > +		return false;
> > +	}
> > +
> > +	return true;
> > +}
> 
> Apologies for rehashing something we dicussed in v1...
> 
> Enforcing the pKVM policy as a denylist rather than an allowlist
> deserves a bit more elaboration, at least in the form of a comment. I
> understand that we must trust EL3 by construction, but it is fuzzy why
> it gets extended to what EL1 might do with FF-A calls that are unknown
> to pKVM.

Sure thing, I'll add a comment for the next version.

> Broadening the scope for a moment, is my understanding correct that
> limiting 'unknown' SMCs from host EL1 are an explicit non-goal of pKVM's
> security model? Assuming a well-intentioned EL3, I'm just a bit worried
> about any vendor-specific junkware that could be used by a malicious
> EL1.

It's a valid concern, but the sad reality is that every shipping Android
device makes use of 'unknown' SMCs and if we reject them at EL2 then the
device won't function properly and we've shot ourselves in the foot.

So we basically have two options:

  (1) Add per-device logic to EL2 which knows how to introspect the
      'unknown' SMCs and filter out bad requests from EL1

  (2) Let them through by default, intercepting standard requests such
      as PSCI and FF-A at EL2 and rely on the firmware not to expose
      non-standard memory sharing calls

We have patches in Android to support modules loading code into EL2,
which makes option (1) practical, but without that support upstream, (2)
is the best we can do for now.

Will

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

[Will Deacon]

Hey Oliver,

On Wed, May 10, 2023 at 08:50:39PM +0000, Oliver Upton wrote:
> On Wed, Apr 19, 2023 at 01:20:45PM +0100, Will Deacon wrote:
> > 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(+)

[...]

> > +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;
> > +}
> 
> </snip>
> 
> I understand SPMD is significant in the context of the whole FF-A spec,
> but I don't think the degree of precision is necessary to get the point
> across for someone coming at this from a more KVM-centric background.
> 
> So, for the sake of readability, could these helpers be named
> ffa_map_hyp_buffers()/ffa_unmap_hyp_buffers() (or similar)? Sticking
> 'hyp' in there somewhere helps the reader understand exactly what is
> getting mapped, since there are both hyp and host buffers.
> 
> Apologies for bikeshedding, but I want to make sure folks w/o knowledge
> of FF-A can at least grasp some of the mechanics here.

It's no skin off my back, we can name them whatever you like!

The only thing I ask is that we're consistent, so if it's ok with you,
I'll rename all the 'spmd_' functions to 'ffa_'.

> > +static void do_ffa_rxtx_map(struct arm_smccc_res *res,
> > +			    struct kvm_cpu_context *ctxt)
> 
> This could do with some clarifying comments as well, since there is
> rather significant interaction between host MAP calls and how we handle
> host/hyp buffers.

Is there something in particular you think needs to be clarified? The
function looks pretty straightforward to me, but then I'm used to it by
now. I'd just like to avoid writing a comment that basically describes
how the code works because that doesn't help anybody.

Will

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Re: [PATCH v2 01/10] KVM: arm64: Block unsafe FF-A calls from the host

[Oliver Upton]

On Mon, May 22, 2023 at 12:22:20PM +0100, Will Deacon wrote:
> Hi Oliver,
> 
> On Wed, May 10, 2023 at 07:08:01PM +0000, Oliver Upton wrote:
> > On Wed, Apr 19, 2023 at 01:20:42PM +0100, Will Deacon wrote:
> > > +/*
> > > + * Is a given FFA function supported, either by forwarding on directly
> > > + * or by handling at EL2?
> > > + */
> > > +static bool ffa_call_supported(u64 func_id)
> > > +{
> > > +	switch (func_id) {
> > > +	/* Unsupported memory management calls */
> > > +	case FFA_FN64_MEM_RETRIEVE_REQ:
> > > +	case FFA_MEM_RETRIEVE_RESP:
> > > +	case FFA_MEM_RELINQUISH:
> > > +	case FFA_MEM_OP_PAUSE:
> > > +	case FFA_MEM_OP_RESUME:
> > > +	case FFA_MEM_FRAG_RX:
> > > +	case FFA_FN64_MEM_DONATE:
> > > +	/* Indirect message passing via RX/TX buffers */
> > > +	case FFA_MSG_SEND:
> > > +	case FFA_MSG_POLL:
> > > +	case FFA_MSG_WAIT:
> > > +	/* 32-bit variants of 64-bit calls */
> > > +	case FFA_MSG_SEND_DIRECT_REQ:
> > > +	case FFA_MSG_SEND_DIRECT_RESP:
> > > +	case FFA_RXTX_MAP:
> > > +	case FFA_MEM_DONATE:
> > > +	case FFA_MEM_RETRIEVE_REQ:
> > > +	/* Don't advertise any features just yet */
> > > +	case FFA_FEATURES:
> > > +		return false;
> > > +	}
> > > +
> > > +	return true;
> > > +}
> > 
> > Apologies for rehashing something we dicussed in v1...
> > 
> > Enforcing the pKVM policy as a denylist rather than an allowlist
> > deserves a bit more elaboration, at least in the form of a comment. I
> > understand that we must trust EL3 by construction, but it is fuzzy why
> > it gets extended to what EL1 might do with FF-A calls that are unknown
> > to pKVM.
> 
> Sure thing, I'll add a comment for the next version.
> 
> > Broadening the scope for a moment, is my understanding correct that
> > limiting 'unknown' SMCs from host EL1 are an explicit non-goal of pKVM's
> > security model? Assuming a well-intentioned EL3, I'm just a bit worried
> > about any vendor-specific junkware that could be used by a malicious
> > EL1.
> 
> It's a valid concern, but the sad reality is that every shipping Android
> device makes use of 'unknown' SMCs and if we reject them at EL2 then the
> device won't function properly and we've shot ourselves in the foot.
> 
> So we basically have two options:
> 
>   (1) Add per-device logic to EL2 which knows how to introspect the
>       'unknown' SMCs and filter out bad requests from EL1
> 
>   (2) Let them through by default, intercepting standard requests such
>       as PSCI and FF-A at EL2 and rely on the firmware not to expose
>       non-standard memory sharing calls
> 
> We have patches in Android to support modules loading code into EL2,
> which makes option (1) practical, but without that support upstream, (2)
> is the best we can do for now.

Thanks, and fully understand what led to the policy you folks have
implemented. Perhaps in the future we can add an optional, restrictive
model to satisfy users that have a more adversarial relationship with
firmware interfaces. Not worth addressing in this series, though.

Going forwared, can the goals/non-goals of the current pKVM design be
captured somewhere in documentation? I think this can be done
organically as more bits and pieces are upstreamed, but it'd help
reviewers who haven't spent time in the trenches with pKVM to at least
grasp the intent. At least personally, I really like to see the pKVM
stuff landing upstream but haven't had first-hand experience with the
horrors of client devices :)

-- 
Thanks,
Oliver

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