Re: [Qemu-devel] [PATCH v2 04/10] target-mips: get_physical_address: Add KVM awareness

[Aurelien Jarno <aurelien@aurel32.net>]

On Mon, Dec 16, 2013 at 02:12:39PM +0000, James Hogan wrote:
> 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(-)
> 
> diff --git a/target-mips/helper.c b/target-mips/helper.c
> index 2e96655..c4be887 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;
>          }

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net