KVM: arm/arm64: Cleanup MMIO handling

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>

diff --git a/arch/arm/include/asm/kvm_emulate.h b/arch/arm/include/asm/kvm_emulate.h
index 08d9805f613b667a57a710d16d0817826ac04b3f..3944305e81df6be1d5ebb6fc406acce08cdb1f55 100644 (file)
--- a/arch/arm/include/asm/kvm_emulate.h
+++ b/arch/arm/include/asm/kvm_emulate.h
@@ -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;
        }
 }
 

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 556cd818eccf3d0b8854cdb4ac639beb698cc450..bd2233805d995752df814d1f8e5d18f01c99ea2d 100644 (file)
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -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)

diff --git a/arch/arm/include/asm/kvm_hyp.h b/arch/arm/include/asm/kvm_hyp.h
index 40e9034db6013bc9afe6013a9ed3e22891d39fad..3c1b55ecc5783514be128d0f1d1f5746bbb607b4 100644 (file)
--- a/arch/arm/include/asm/kvm_hyp.h
+++ b/arch/arm/include/asm/kvm_hyp.h
@@ -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

diff --git a/arch/arm/include/asm/kvm_mmio.h b/arch/arm/include/asm/kvm_mmio.h
deleted file mode 100644 (file)
index 32fbf82..0000000
--- a/arch/arm/include/asm/kvm_mmio.h
+++ /dev/null
@@ -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__ */

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 53ea7637b7b23c18a79ee444f3e597b5601b5942..688c63412cc27922aa2b5faba8d8fc808bef674b 100644 (file)
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -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);
 }

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index c61260cf63c5889d933ff4ee6fa68c33fae7dbed..f6a77ddab956f048bf5afbc8e955d3d33b9f13b4 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -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);
 

diff --git a/arch/arm64/include/asm/kvm_mmio.h b/arch/arm64/include/asm/kvm_mmio.h
deleted file mode 100644 (file)
index b204501..0000000
--- a/arch/arm64/include/asm/kvm_mmio.h
+++ /dev/null
@@ -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__ */

diff --git a/virt/kvm/arm/mmio.c b/virt/kvm/arm/mmio.c
index 1bb71acd53f221fe241c905a78c1d34f1318a414..aedfcff99ac58000cbfea8ce9f10a37df8f61b6e 100644 (file)
--- a/virt/kvm/arm/mmio.c
+++ b/virt/kvm/arm/mmio.c
@@ -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),

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index e3ad950131920437a33554d1361d35b7db368d7a..a4fa81d75e84da4f0dc3ecf8df0355369766b102 100644 (file)
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -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>