mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

KVM: arm64: nVHE: Switch to hyp context for EL2 

Save and restore the host context when switching to and from hyp. This
gives hyp its own context that the host will not see as a step towards a
full trust boundary between the two.

SP_EL0 and pointer authentication keys are currently shared between the
host and hyp so don't need to be switched yet.

Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915104643.2543892-13-ascull@google.com
This commit is contained in:
Andrew Scull 2020-09-15 11:46:36 +01:00 committed by Marc Zyngier
parent 603d2bdaa5
commit 4e3393a969
4 changed files with 89 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/arm64/kvm/hyp/include/hyp/switch.h
View File

@ -372,6 +372,8 @@ static inline bool esr_is_ptrauth_trap(u32 esr)
ctxt_sys_reg(ctxt, key ## KEYHI_EL1) = __val; \
} while(0)
DECLARE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
static inline bool __hyp_handle_ptrauth(struct kvm_vcpu *vcpu)
{
struct kvm_cpu_context *ctxt;

2
arch/arm64/kvm/hyp/nvhe/Makefile
View File

@ -6,7 +6,7 @@
asflags-y := -D__KVM_NVHE_HYPERVISOR__
ccflags-y := -D__KVM_NVHE_HYPERVISOR__
obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o
obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o hyp-main.o
obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
../fpsimd.o ../hyp-entry.o

68
arch/arm64/kvm/hyp/nvhe/host.S
View File

@ -12,6 +12,55 @@
.text
SYM_FUNC_START(__host_exit)
stp x0, x1, [sp, #-16]!
get_host_ctxt x0, x1
ALTERNATIVE(nop, SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
/* Store the host regs x2 and x3 */
stp x2, x3, [x0, #CPU_XREG_OFFSET(2)]
/* Retrieve the host regs x0-x1 from the stack */
ldp x2, x3, [sp], #16 // x0, x1
/* Store the host regs x0-x1 and x4-x17 */
stp x2, x3, [x0, #CPU_XREG_OFFSET(0)]
stp x4, x5, [x0, #CPU_XREG_OFFSET(4)]
stp x6, x7, [x0, #CPU_XREG_OFFSET(6)]
stp x8, x9, [x0, #CPU_XREG_OFFSET(8)]
stp x10, x11, [x0, #CPU_XREG_OFFSET(10)]
stp x12, x13, [x0, #CPU_XREG_OFFSET(12)]
stp x14, x15, [x0, #CPU_XREG_OFFSET(14)]
stp x16, x17, [x0, #CPU_XREG_OFFSET(16)]
/* Store the host regs x18-x29, lr */
save_callee_saved_regs x0
/* Save the host context pointer in x29 across the function call */
mov x29, x0
bl handle_trap
/* Restore host regs x0-x17 */
ldp x0, x1, [x29, #CPU_XREG_OFFSET(0)]
ldp x2, x3, [x29, #CPU_XREG_OFFSET(2)]
ldp x4, x5, [x29, #CPU_XREG_OFFSET(4)]
ldp x6, x7, [x29, #CPU_XREG_OFFSET(6)]
ldp x8, x9, [x29, #CPU_XREG_OFFSET(8)]
ldp x10, x11, [x29, #CPU_XREG_OFFSET(10)]
ldp x12, x13, [x29, #CPU_XREG_OFFSET(12)]
ldp x14, x15, [x29, #CPU_XREG_OFFSET(14)]
ldp x16, x17, [x29, #CPU_XREG_OFFSET(16)]
/* Restore host regs x18-x29, lr */
restore_callee_saved_regs x29
/* Do not touch any register after this! */
eret
sb
SYM_FUNC_END(__host_exit)
SYM_FUNC_START(__hyp_do_panic)
mov lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\
PSR_MODE_EL1h)
@ -34,7 +83,7 @@ SYM_FUNC_END(__hyp_do_panic)
/* Check for a stub HVC call */
cmp x0, #HVC_STUB_HCALL_NR
b.hs 1f
b.hs __host_exit
/*
* Compute the idmap address of __kvm_handle_stub_hvc and
@ -50,23 +99,6 @@ SYM_FUNC_END(__hyp_do_panic)
/* x5 = __pa(x5) */
sub x5, x5, x6
br x5
1:
/*
* Shuffle the parameters before calling the function
* pointed to in x0. Assumes parameters in x[1,2,3].
*/
kern_hyp_va x0
str lr, [sp, #-16]!
mov lr, x0
mov x0, x1
mov x1, x2
mov x2, x3
blr lr
ldr lr, [sp], #16
eret
sb
.L__vect_end\@:
.if ((.L__vect_end\@ - .L__vect_start\@) > 0x80)
.error "host_el1_sync_vect larger than vector entry"

36
arch/arm64/kvm/hyp/nvhe/hyp-main.c Normal file
View File

@ -0,0 +1,36 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2020 - Google Inc
* Author: Andrew Scull <ascull@google.com>
*/
#include <hyp/switch.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>
#include <asm/kvm_host.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
typedef unsigned long (*hypcall_fn_t)
(unsigned long, unsigned long, unsigned long);
void handle_trap(struct kvm_cpu_context *host_ctxt)
{
u64 esr = read_sysreg_el2(SYS_ESR);
hypcall_fn_t func;
unsigned long ret;
if (ESR_ELx_EC(esr) != ESR_ELx_EC_HVC64)
hyp_panic();
/*
* __kvm_call_hyp takes a pointer in the host address space and
* up to three arguments.
*/
func = (hypcall_fn_t)kern_hyp_va(host_ctxt->regs.regs[0]);
ret = func(host_ctxt->regs.regs[1],
host_ctxt->regs.regs[2],
host_ctxt->regs.regs[3]);
host_ctxt->regs.regs[0] = ret;
}