diff mbox

[v4,04/10] target-mips: get_physical_address: Add KVM awareness

Message ID 1394801281-18997-5-git-send-email-james.hogan@imgtec.com (mailing list archive)
State New, archived
Headers show

Commit Message

James Hogan March 14, 2014, 12:47 p.m. UTC 
MIPS KVM trap & emulate mode (which is currently the only supported
mode) has to add an extra kseg0/kseg1 at 0x40000000 and an extra
kseg2/kseg3 at 0x60000000. Take this into account in
get_physical_address() so that debug memory access works.

This is done by translating the address to a standard kseg0 or kseg2
address before doing the normal address translation. The real virtual
address is still used for TLB lookups.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
---
 target-mips/helper.c | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

Comments

Paolo Bonzini March 19, 2014, 4:33 p.m. UTC | #1 
Il 14/03/2014 13:47, James Hogan ha scritto:
> +    if (kvm_enabled()) {
> +        /* KVM T&E adds guest kernel segments in useg */
> +        if (real_address >= KVM_KSEG0_BASE) {
> +            if (real_address < KVM_KSEG2_BASE) {
> +                /* kseg0 */
> +                address += KSEG0_BASE - KVM_KSEG0_BASE;
> +            } else if (real_address <= USEG_LIMIT) {
> +                /* kseg2/3 */
> +                address += KSEG2_BASE - KVM_KSEG2_BASE;
> +            }
> +        }
> +    }

Besides changing the segment bases, is there anything else to do to run 
KVM-enabled kernels under TCG?  (I know nothing about MIPS and it 
shows).  We should consider adding a knob to run them in TCG mode.

This is not blocking this series, and I'm okay with helping or even 
doing the work, if somebody tells me what to do. :)

Paolo
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James Hogan March 20, 2014, 10:08 a.m. UTC | #2 
On 19/03/14 16:33, Paolo Bonzini wrote:
> Il 14/03/2014 13:47, James Hogan ha scritto:
>> +    if (kvm_enabled()) {
>> +        /* KVM T&E adds guest kernel segments in useg */
>> +        if (real_address >= KVM_KSEG0_BASE) {
>> +            if (real_address < KVM_KSEG2_BASE) {
>> +                /* kseg0 */
>> +                address += KSEG0_BASE - KVM_KSEG0_BASE;
>> +            } else if (real_address <= USEG_LIMIT) {
>> +                /* kseg2/3 */
>> +                address += KSEG2_BASE - KVM_KSEG2_BASE;
>> +            }
>> +        }
>> +    }
> 
> Besides changing the segment bases, is there anything else to do to run
> KVM-enabled kernels under TCG?  (I know nothing about MIPS and it
> shows).  We should consider adding a knob to run them in TCG mode.
> 
> This is not blocking this series, and I'm okay with helping or even
> doing the work, if somebody tells me what to do. :)

That's a good idea. It's pretty much just the extra segments I think. In
TCG mode the bootloader wouldn't even need to do anything different
since it can translate fine from the reset vector in kseg1 (where a KVM
guest cannot execute from) and it'll still jump to the kernel entry
point from the ELF.

I'll add it to my list :)

Cheers
James
diff mbox

Patch

diff --git a/target-mips/helper.c b/target-mips/helper.c
index 2b30fc2..4053d50 100644
--- a/target-mips/helper.c
+++ b/target-mips/helper.c
@@ -24,6 +24,7 @@ 
 #include <signal.h>
 
 #include "cpu.h"
+#include "sysemu/kvm.h"
 
 enum {
     TLBRET_DIRTY = -4,
@@ -100,7 +101,7 @@  int r4k_map_address (CPUMIPSState *env, hwaddr *physical, int *prot,
 }
 
 static int get_physical_address (CPUMIPSState *env, hwaddr *physical,
-                                int *prot, target_ulong address,
+                                int *prot, target_ulong real_address,
                                 int rw, int access_type)
 {
     /* User mode can only access useg/xuseg */
@@ -113,6 +114,8 @@  static int get_physical_address (CPUMIPSState *env, hwaddr *physical,
     int KX = (env->CP0_Status & (1 << CP0St_KX)) != 0;
 #endif
     int ret = TLBRET_MATCH;
+    /* effective address (modified for KVM T&E kernel segments) */
+    target_ulong address = real_address;
 
 #if 0
     qemu_log("user mode %d h %08x\n", user_mode, env->hflags);
@@ -124,19 +127,35 @@  static int get_physical_address (CPUMIPSState *env, hwaddr *physical,
 #define KSEG2_BASE      0xC0000000UL
 #define KSEG3_BASE      0xE0000000UL
 
+#define KVM_KSEG0_BASE  0x40000000UL
+#define KVM_KSEG2_BASE  0x60000000UL
+
+    if (kvm_enabled()) {
+        /* KVM T&E adds guest kernel segments in useg */
+        if (real_address >= KVM_KSEG0_BASE) {
+            if (real_address < KVM_KSEG2_BASE) {
+                /* kseg0 */
+                address += KSEG0_BASE - KVM_KSEG0_BASE;
+            } else if (real_address <= USEG_LIMIT) {
+                /* kseg2/3 */
+                address += KSEG2_BASE - KVM_KSEG2_BASE;
+            }
+        }
+    }
+
     if (address <= USEG_LIMIT) {
         /* useg */
         if (env->CP0_Status & (1 << CP0St_ERL)) {
             *physical = address & 0xFFFFFFFF;
             *prot = PAGE_READ | PAGE_WRITE;
         } else {
-            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);
+            ret = env->tlb->map_address(env, physical, prot, real_address, rw, access_type);
         }
 #if defined(TARGET_MIPS64)
     } else if (address < 0x4000000000000000ULL) {
         /* xuseg */
         if (UX && address <= (0x3FFFFFFFFFFFFFFFULL & env->SEGMask)) {
-            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);
+            ret = env->tlb->map_address(env, physical, prot, real_address, rw, access_type);
         } else {
             ret = TLBRET_BADADDR;
         }
@@ -144,7 +163,7 @@  static int get_physical_address (CPUMIPSState *env, hwaddr *physical,
         /* xsseg */
         if ((supervisor_mode || kernel_mode) &&
             SX && address <= (0x7FFFFFFFFFFFFFFFULL & env->SEGMask)) {
-            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);
+            ret = env->tlb->map_address(env, physical, prot, real_address, rw, access_type);
         } else {
             ret = TLBRET_BADADDR;
         }
@@ -161,7 +180,7 @@  static int get_physical_address (CPUMIPSState *env, hwaddr *physical,
         /* xkseg */
         if (kernel_mode && KX &&
             address <= (0xFFFFFFFF7FFFFFFFULL & env->SEGMask)) {
-            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);
+            ret = env->tlb->map_address(env, physical, prot, real_address, rw, access_type);
         } else {
             ret = TLBRET_BADADDR;
         }
@@ -185,7 +204,7 @@  static int get_physical_address (CPUMIPSState *env, hwaddr *physical,
     } else if (address < (int32_t)KSEG3_BASE) {
         /* sseg (kseg2) */
         if (supervisor_mode || kernel_mode) {
-            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);
+            ret = env->tlb->map_address(env, physical, prot, real_address, rw, access_type);
         } else {
             ret = TLBRET_BADADDR;
         }
@@ -193,7 +212,7 @@  static int get_physical_address (CPUMIPSState *env, hwaddr *physical,
         /* kseg3 */
         /* XXX: debug segment is not emulated */
         if (kernel_mode) {
-            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);
+            ret = env->tlb->map_address(env, physical, prot, real_address, rw, access_type);
         } else {
             ret = TLBRET_BADADDR;
         }