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KVM: arm/arm64: Cleanup MMIO handling

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Our MMIO handling is a bit odd, in the sense that it uses an
intermediate per-vcpu structure to store the various decoded
information that describe the access.

But the same information is readily available in the HSR/ESR_EL2
field, and we actually use this field to populate the structure.

Let's simplify the whole thing by getting rid of the superfluous
structure and save a (tiny) bit of space in the vcpu structure.

[32bit fix courtesy of Olof Johansson <olof@lixom.net>]
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2019-12-13 13:25:25 +00:00
parent 31a9b0b11b
commit 0e20f5e255
9 changed files with 42 additions and 117 deletions
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5
arch/arm/include/asm/kvm_emulate.h
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@ -9,7 +9,6 @@
#include <linux/kvm_host.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_mmio.h>
#include <asm/kvm_arm.h>
#include <asm/cputype.h>
@ -220,7 +219,7 @@ static inline bool kvm_vcpu_dabt_is_cm(struct kvm_vcpu *vcpu)
}
/* Get Access Size from a data abort */
static inline int kvm_vcpu_dabt_get_as(struct kvm_vcpu *vcpu)
static inline unsigned int kvm_vcpu_dabt_get_as(struct kvm_vcpu *vcpu)
{
switch ((kvm_vcpu_get_hsr(vcpu) >> 22) & 0x3) {
case 0:
@ -231,7 +230,7 @@ static inline int kvm_vcpu_dabt_get_as(struct kvm_vcpu *vcpu)
return 4;
default:
kvm_err("Hardware is weird: SAS 0b11 is reserved\n");
return -EFAULT;
return 4;
}
}

12
arch/arm/include/asm/kvm_host.h
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@ -14,7 +14,6 @@
#include <asm/cputype.h>
#include <asm/kvm.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_mmio.h>
#include <asm/fpstate.h>
#include <kvm/arm_arch_timer.h>
@ -202,9 +201,6 @@ struct kvm_vcpu_arch {
/* Don't run the guest (internal implementation need) */
bool pause;
/* IO related fields */
struct kvm_decode mmio_decode;
/* Cache some mmu pages needed inside spinlock regions */
struct kvm_mmu_memory_cache mmu_page_cache;
@ -300,6 +296,14 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
static inline void handle_exit_early(struct kvm_vcpu *vcpu, struct kvm_run *run,
int exception_index) {}
/* MMIO helpers */
void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data);
unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
phys_addr_t fault_ipa);
static inline void __cpu_init_hyp_mode(phys_addr_t pgd_ptr,
unsigned long hyp_stack_ptr,
unsigned long vector_ptr)

1
arch/arm/include/asm/kvm_hyp.h
View File

@ -10,6 +10,7 @@
#include <linux/compiler.h>
#include <linux/kvm_host.h>
#include <asm/cp15.h>
#include <asm/kvm_arm.h>
#include <asm/vfp.h>
#define __hyp_text __section(.hyp.text) notrace

28
arch/arm/include/asm/kvm_mmio.h
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@ -1,28 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2012 - Virtual Open Systems and Columbia University
* Author: Christoffer Dall <c.dall@virtualopensystems.com>
*/
#ifndef __ARM_KVM_MMIO_H__
#define __ARM_KVM_MMIO_H__
#include <linux/kvm_host.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_arm.h>
struct kvm_decode {
unsigned long rt;
bool sign_extend;
/* Not used on 32-bit arm */
bool sixty_four;
};
void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data);
unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
phys_addr_t fault_ipa);
#endif /* __ARM_KVM_MMIO_H__ */

3
arch/arm64/include/asm/kvm_emulate.h
View File

@ -17,7 +17,6 @@
#include <asm/esr.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmio.h>
#include <asm/ptrace.h>
#include <asm/cputype.h>
#include <asm/virt.h>
@ -341,7 +340,7 @@ static inline bool kvm_vcpu_dabt_is_cm(const struct kvm_vcpu *vcpu)
return !!(kvm_vcpu_get_hsr(vcpu) & ESR_ELx_CM);
}
static inline int kvm_vcpu_dabt_get_as(const struct kvm_vcpu *vcpu)
static inline unsigned int kvm_vcpu_dabt_get_as(const struct kvm_vcpu *vcpu)
{
return 1 << ((kvm_vcpu_get_hsr(vcpu) & ESR_ELx_SAS) >> ESR_ELx_SAS_SHIFT);
}

12
arch/arm64/include/asm/kvm_host.h
View File

@ -24,7 +24,6 @@
#include <asm/fpsimd.h>
#include <asm/kvm.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_mmio.h>
#include <asm/thread_info.h>
#define __KVM_HAVE_ARCH_INTC_INITIALIZED
@ -325,9 +324,6 @@ struct kvm_vcpu_arch {
/* Don't run the guest (internal implementation need) */
bool pause;
/* IO related fields */
struct kvm_decode mmio_decode;
/* Cache some mmu pages needed inside spinlock regions */
struct kvm_mmu_memory_cache mmu_page_cache;
@ -491,6 +487,14 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
void handle_exit_early(struct kvm_vcpu *vcpu, struct kvm_run *run,
int exception_index);
/* MMIO helpers */
void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data);
unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
phys_addr_t fault_ipa);
int kvm_perf_init(void);
int kvm_perf_teardown(void);

27
arch/arm64/include/asm/kvm_mmio.h
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@ -1,27 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2012 - Virtual Open Systems and Columbia University
* Author: Christoffer Dall <c.dall@virtualopensystems.com>
*/
#ifndef __ARM64_KVM_MMIO_H__
#define __ARM64_KVM_MMIO_H__
#include <linux/kvm_host.h>
#include <asm/kvm_arm.h>
struct kvm_decode {
unsigned long rt;
bool sign_extend;
/* Witdth of the register accessed by the faulting instruction is 64-bits */
bool sixty_four;
};
void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data);
unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
phys_addr_t fault_ipa);
#endif /* __ARM64_KVM_MMIO_H__ */

70
virt/kvm/arm/mmio.c
View File

@ -5,7 +5,6 @@
*/
#include <linux/kvm_host.h>
#include <asm/kvm_mmio.h>
#include <asm/kvm_emulate.h>
#include <trace/events/kvm.h>
@ -92,26 +91,23 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
vcpu->mmio_needed = 0;
if (!run->mmio.is_write) {
len = run->mmio.len;
if (len > sizeof(unsigned long))
return -EINVAL;
if (!kvm_vcpu_dabt_iswrite(vcpu)) {
len = kvm_vcpu_dabt_get_as(vcpu);
data = kvm_mmio_read_buf(run->mmio.data, len);
if (vcpu->arch.mmio_decode.sign_extend &&
if (kvm_vcpu_dabt_issext(vcpu) &&
len < sizeof(unsigned long)) {
mask = 1U << ((len * 8) - 1);
data = (data ^ mask) - mask;
}
if (!vcpu->arch.mmio_decode.sixty_four)
if (!kvm_vcpu_dabt_issf(vcpu))
data = data & 0xffffffff;
trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
&data);
data = vcpu_data_host_to_guest(vcpu, data, len);
vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data);
}
/*
@ -123,36 +119,6 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
return 0;
}
static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)
{
unsigned long rt;
int access_size;
bool sign_extend;
bool sixty_four;
if (kvm_vcpu_dabt_iss1tw(vcpu)) {
/* page table accesses IO mem: tell guest to fix its TTBR */
kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
return 1;
}
access_size = kvm_vcpu_dabt_get_as(vcpu);
if (unlikely(access_size < 0))
return access_size;
*is_write = kvm_vcpu_dabt_iswrite(vcpu);
sign_extend = kvm_vcpu_dabt_issext(vcpu);
sixty_four = kvm_vcpu_dabt_issf(vcpu);
rt = kvm_vcpu_dabt_get_rd(vcpu);
*len = access_size;
vcpu->arch.mmio_decode.sign_extend = sign_extend;
vcpu->arch.mmio_decode.rt = rt;
vcpu->arch.mmio_decode.sixty_four = sixty_four;
return 0;
}
int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
phys_addr_t fault_ipa)
{
@ -164,15 +130,10 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
u8 data_buf[8];
/*
* Prepare MMIO operation. First decode the syndrome data we get
* from the CPU. Then try if some in-kernel emulation feels
* responsible, otherwise let user space do its magic.
* No valid syndrome? Ask userspace for help if it has
* voluntered to do so, and bail out otherwise.
*/
if (kvm_vcpu_dabt_isvalid(vcpu)) {
ret = decode_hsr(vcpu, &is_write, &len);
if (ret)
return ret;
} else {
if (!kvm_vcpu_dabt_isvalid(vcpu)) {
if (vcpu->kvm->arch.return_nisv_io_abort_to_user) {
run->exit_reason = KVM_EXIT_ARM_NISV;
run->arm_nisv.esr_iss = kvm_vcpu_dabt_iss_nisv_sanitized(vcpu);
@ -184,7 +145,20 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
return -ENOSYS;
}
rt = vcpu->arch.mmio_decode.rt;
/* Page table accesses IO mem: tell guest to fix its TTBR */
if (kvm_vcpu_dabt_iss1tw(vcpu)) {
kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
return 1;
}
/*
* Prepare MMIO operation. First decode the syndrome data we get
* from the CPU. Then try if some in-kernel emulation feels
* responsible, otherwise let user space do its magic.
*/
is_write = kvm_vcpu_dabt_iswrite(vcpu);
len = kvm_vcpu_dabt_get_as(vcpu);
rt = kvm_vcpu_dabt_get_rd(vcpu);
if (is_write) {
data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),

1
virt/kvm/arm/mmu.c
View File

@ -14,7 +14,6 @@
#include <asm/cacheflush.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_mmio.h>
#include <asm/kvm_ras.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>