diff mbox series

[RFC,v2,15/18] guest memory protection: Decouple kvm_memcrypt_*() helpers from KVM

Message ID 20200521034304.340040-16-david@gibson.dropbear.id.au
State New, archived
Headers show
Series Refactor configuration of guest memory protection | expand

Commit Message

David Gibson May 21, 2020, 3:43 a.m. UTC
The kvm_memcrypt_enabled() and kvm_memcrypt_encrypt_data() helper functions
don't conceptually have any connection to KVM (although it's not possible
in practice to use them without it).

They also rely on looking at the global KVMState.  But the same information
is available from the machine, and the only existing callers have natural
access to the machine state.

Therefore, move and rename them to helpers in guest-memory-protection.h,
taking an explicit machine parameter.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 accel/kvm/kvm-all.c                    | 28 -------------------
 accel/stubs/kvm-stub.c                 | 10 -------
 hw/i386/pc_sysfw.c                     |  6 ++--
 include/exec/guest-memory-protection.h | 38 ++++++++++++++++++++++++++
 include/sysemu/kvm.h                   | 17 ------------
 5 files changed, 42 insertions(+), 57 deletions(-)

Comments

Richard Henderson June 2, 2020, 4:13 a.m. UTC | #1
On 5/20/20 8:43 PM, David Gibson wrote:
> The kvm_memcrypt_enabled() and kvm_memcrypt_encrypt_data() helper functions
> don't conceptually have any connection to KVM (although it's not possible
> in practice to use them without it).

Yet?

I would expect TCG implementations of these interfaces eventually, for
simulation of such hardware.  Or are we expecting *this* interface to be used
only with kvm/any-other-hw-accel, as the nested guest inside of the outermost
tcg qemu that's simulating hardware that supports...

Anyway, the actual code looks ok.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~
David Gibson June 3, 2020, 10:18 a.m. UTC | #2
On Mon, Jun 01, 2020 at 09:13:01PM -0700, Richard Henderson wrote:
> On 5/20/20 8:43 PM, David Gibson wrote:
> > The kvm_memcrypt_enabled() and kvm_memcrypt_encrypt_data() helper functions
> > don't conceptually have any connection to KVM (although it's not possible
> > in practice to use them without it).
> 
> Yet?
> 
> I would expect TCG implementations of these interfaces eventually, for
> simulation of such hardware.  Or are we expecting *this* interface to be used
> only with kvm/any-other-hw-accel, as the nested guest inside of the outermost
> tcg qemu that's simulating hardware that supports...

Yes, this.  The whole point of this stuff is that the guest is
protected *from the hypervisor*, and therefore qemu can't expect to
access guest memory.  It's hard to imagine any way TCG could deal with
that.

An implementation for a non-KVM accelerator is entirely plausible, on
the other hand.
diff mbox series

Patch

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 3588adf1e1..1b10e94222 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -118,9 +118,6 @@  struct KVMState
     KVMMemoryListener memory_listener;
     QLIST_HEAD(, KVMParkedVcpu) kvm_parked_vcpus;
 
-    /* memory encryption */
-    GuestMemoryProtection *guest_memory_protection;
-
     /* For "info mtree -f" to tell if an MR is registered in KVM */
     int nr_as;
     struct KVMAs {
@@ -169,29 +166,6 @@  int kvm_get_max_memslots(void)
     return s->nr_slots;
 }
 
-bool kvm_memcrypt_enabled(void)
-{
-    if (kvm_state && kvm_state->guest_memory_protection) {
-        return true;
-    }
-
-    return false;
-}
-
-int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len)
-{
-    GuestMemoryProtection *gmpo = kvm_state->guest_memory_protection;
-
-    if (gmpo) {
-        GuestMemoryProtectionClass *gmpc =
-            GUEST_MEMORY_PROTECTION_GET_CLASS(gmpo);
-
-        return gmpc->encrypt_data(gmpo, ptr, len);
-    }
-
-    return 1;
-}
-
 /* Called with KVMMemoryListener.slots_lock held */
 static KVMSlot *kvm_get_free_slot(KVMMemoryListener *kml)
 {
@@ -2110,8 +2084,6 @@  static int kvm_init(MachineState *ms)
         if (ret < 0) {
             goto err;
         }
-
-        kvm_state->guest_memory_protection = ms->gmpo;
     }
 
     ret = kvm_arch_init(ms, s);
diff --git a/accel/stubs/kvm-stub.c b/accel/stubs/kvm-stub.c
index 82f118d2df..78b3eef117 100644
--- a/accel/stubs/kvm-stub.c
+++ b/accel/stubs/kvm-stub.c
@@ -104,16 +104,6 @@  int kvm_on_sigbus(int code, void *addr)
     return 1;
 }
 
-bool kvm_memcrypt_enabled(void)
-{
-    return false;
-}
-
-int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len)
-{
-  return 1;
-}
-
 #ifndef CONFIG_USER_ONLY
 int kvm_irqchip_add_msi_route(KVMState *s, int vector, PCIDevice *dev)
 {
diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index b8d8ef59eb..9cef5f7780 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -38,6 +38,7 @@ 
 #include "sysemu/sysemu.h"
 #include "hw/block/flash.h"
 #include "sysemu/kvm.h"
+#include "exec/guest-memory-protection.h"
 
 /*
  * We don't have a theoretically justifiable exact lower bound on the base
@@ -196,10 +197,11 @@  static void pc_system_flash_map(PCMachineState *pcms,
             pc_isa_bios_init(rom_memory, flash_mem, size);
 
             /* Encrypt the pflash boot ROM */
-            if (kvm_memcrypt_enabled()) {
+            if (guest_memory_protection_enabled(MACHINE(pcms))) {
                 flash_ptr = memory_region_get_ram_ptr(flash_mem);
                 flash_size = memory_region_size(flash_mem);
-                ret = kvm_memcrypt_encrypt_data(flash_ptr, flash_size);
+                ret = guest_memory_protection_encrypt(MACHINE(pcms),
+                                                      flash_ptr, flash_size);
                 if (ret) {
                     error_report("failed to encrypt pflash rom");
                     exit(1);
diff --git a/include/exec/guest-memory-protection.h b/include/exec/guest-memory-protection.h
index 3707b96515..7d959b4910 100644
--- a/include/exec/guest-memory-protection.h
+++ b/include/exec/guest-memory-protection.h
@@ -14,6 +14,7 @@ 
 #define QEMU_GUEST_MEMORY_PROTECTION_H
 
 #include "qom/object.h"
+#include "hw/boards.h"
 
 typedef struct GuestMemoryProtection GuestMemoryProtection;
 
@@ -35,5 +36,42 @@  typedef struct GuestMemoryProtectionClass {
     int (*encrypt_data)(GuestMemoryProtection *, uint8_t *, uint64_t);
 } GuestMemoryProtectionClass;
 
+/**
+ * guest_memory_protection_enabled - return whether guest memory is
+ *                                   protected from hypervisor access
+ *                                   (with memory encryption or
+ *                                   otherwise)
+ * Returns: true guest memory is not directly accessible to qemu
+ *          false guest memory is directly accessible to qemu
+ */
+static inline bool guest_memory_protection_enabled(MachineState *machine)
+{
+    return !!machine->gmpo;
+}
+
+/**
+ * guest_memory_protection_encrypt: encrypt the memory range to make
+ *                                  it guest accessible
+ *
+ * Return: 1 failed to encrypt the range
+ *         0 succesfully encrypted memory region
+ */
+static inline int guest_memory_protection_encrypt(MachineState *machine,
+                                                  uint8_t *ptr, uint64_t len)
+{
+    GuestMemoryProtection *gmpo = machine->gmpo;
+
+    if (gmpo) {
+        GuestMemoryProtectionClass *gmpc =
+            GUEST_MEMORY_PROTECTION_GET_CLASS(gmpo);
+
+        if (gmpc->encrypt_data) {
+            return gmpc->encrypt_data(gmpo, ptr, len);
+        }
+    }
+
+    return 1;
+}
+
 #endif /* QEMU_GUEST_MEMORY_PROTECTION_H */
 
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 3b2250471c..cfc4cee995 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -231,23 +231,6 @@  int kvm_destroy_vcpu(CPUState *cpu);
  */
 bool kvm_arm_supports_user_irq(void);
 
-/**
- * kvm_memcrypt_enabled - return boolean indicating whether memory encryption
- *                        is enabled
- * Returns: 1 memory encryption is enabled
- *          0 memory encryption is disabled
- */
-bool kvm_memcrypt_enabled(void);
-
-/**
- * kvm_memcrypt_encrypt_data: encrypt the memory range
- *
- * Return: 1 failed to encrypt the range
- *         0 succesfully encrypted memory region
- */
-int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len);
-
-
 #ifdef NEED_CPU_H
 #include "cpu.h"