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Revert "ANDROID: BACKPORT: KVM: arm64: Block unsafe FF-A calls from the host"

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This reverts commit c63757defd.

Bug: 233587962
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: I6ab696c6ec7f60828061e0bbf2a2466a1b641340
This commit is contained in:
Will Deacon
2022-07-07 15:49:18 +01:00
parent 5b19ef7a56
commit 07e24d0bc7
4 changed files with 1 additions and 133 deletions
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16
arch/arm64/kvm/hyp/include/nvhe/ffa.h
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@@ -1,16 +0,0 @@
/* 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 */

2
arch/arm64/kvm/hyp/nvhe/Makefile
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@@ -19,7 +19,7 @@ lib-objs := $(addprefix ../../../lib/, $(lib-objs))
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 stub.o page_alloc.o \
cache.o ffa.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o
cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o
obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
obj-y += $(lib-objs)

113
arch/arm64/kvm/hyp/nvhe/ffa.c
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@@ -1,113 +0,0 @@
// 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;
}
static bool ffa_call_unsupported(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:
return true;
}
return false;
}
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;
switch (func_id) {
/* Memory management */
case FFA_FN64_RXTX_MAP:
case FFA_RXTX_UNMAP:
case FFA_MEM_SHARE:
case FFA_FN64_MEM_SHARE:
case FFA_MEM_LEND:
case FFA_FN64_MEM_LEND:
case FFA_MEM_RECLAIM:
case FFA_MEM_FRAG_TX:
break;
}
if (!ffa_call_unsupported(func_id))
return false; /* Pass through */
ffa_to_smccc_error(&res, FFA_RET_NOT_SUPPORTED);
ffa_set_retval(host_ctxt, &res);
return true;
}

3
arch/arm64/kvm/hyp/nvhe/hyp-main.c
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@@ -15,7 +15,6 @@
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
#include <nvhe/ffa.h>
#include <nvhe/iommu.h>
#include <nvhe/mem_protect.h>
#include <nvhe/mm.h>
@@ -1053,8 +1052,6 @@ static void handle_host_smc(struct kvm_cpu_context *host_ctxt)
handled = kvm_host_psci_handler(host_ctxt);
if (!handled && kvm_iommu_ops.host_smc_handler)
handled = kvm_iommu_ops.host_smc_handler(host_ctxt);
if (!handled)
handled = kvm_host_ffa_handler(host_ctxt);
if (!handled)
default_host_smc_handler(host_ctxt);