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MTRR support on x86 (Carl-Daniel Hailfinger) 

The current codebase ignores MTRR (Memory Type Range Register)
configuration writes and reads because Qemu does not implement caching.
All BIOS/firmware in know of for x86 do implement a mode called
Cache-as-RAM (CAR) which locks down the CPU cache lines and uses the CPU
cache like RAM before RAM is enabled. Qemu assumes RAM is accessible
from the start, but it would be nice to be able to run real
BIOS/firmware in Qemu. For that, we need CAR support and for CAR support
we have to support MTRRs.

This patch is a first step in that direction. MTRRs are MSRs supported
by all recent x86 CPUs, even old i586. Besides influencing cache, the
MTRRs can be written and read back, so discarding MTRR writes violates
the expectations of existing code out there.

An added benefit of this patch is that it fixes the following Linux
kernel error message present in recent kernels (provided the BIOS has
the recent MTRR patches applied):
 ------------[ cut here ]------------
WARNING: at arch/x86/kernel/cpu/mtrr/main.c:1500 mtrr_trim_uncached_memory+0x382/0x384()
WARNING: strange, CPU MTRRs all blank?
Modules linked in:
Supported: Yes
Pid: 0, comm: swapper Not tainted 2.6.27.7-9-default #1
 [<c0106570>] dump_trace+0x6b/0x249
 [<c01070a5>] show_trace+0x20/0x39
 [<c0343c02>] dump_stack+0x71/0x76
 [<c012acb2>] warn_slowpath+0x6f/0x90
 [<c0542f8f>] mtrr_trim_uncached_memory+0x382/0x384
 [<c053f24d>] setup_arch+0x40d/0x639
 [<c053a6ac>] start_kernel+0x6b/0x31f
 =======================
 ---[ end trace 4eaa2a86a8e2da22 ]---

Handle common x86 MTRR reads and writes, but don't act on them.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6449 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-01-26 17:53:04 +00:00
parent 249aa745fb
commit 165d9b82eb
2 changed files with 106 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
target-i386/cpu.h
View File

@ -261,8 +261,25 @@
#define MSR_IA32_PERF_STATUS 0x198
#define MSR_MTRRphysBase(reg) (0x200 + 2 * (reg))
#define MSR_MTRRphysMask(reg) (0x200 + 2 * (reg) + 1)
#define MSR_MTRRfix64K_00000 0x250
#define MSR_MTRRfix16K_80000 0x258
#define MSR_MTRRfix16K_A0000 0x259
#define MSR_MTRRfix4K_C0000 0x268
#define MSR_MTRRfix4K_C8000 0x269
#define MSR_MTRRfix4K_D0000 0x26a
#define MSR_MTRRfix4K_D8000 0x26b
#define MSR_MTRRfix4K_E0000 0x26c
#define MSR_MTRRfix4K_E8000 0x26d
#define MSR_MTRRfix4K_F0000 0x26e
#define MSR_MTRRfix4K_F8000 0x26f
#define MSR_PAT 0x277
#define MSR_MTRRdefType 0x2ff
#define MSR_EFER 0xc0000080
#define MSR_EFER_SCE (1 << 0)
@ -629,6 +646,14 @@ typedef struct CPUX86State {
uint32_t cpuid_ext3_features;
uint32_t cpuid_apic_id;
/* MTRRs */
uint64_t mtrr_fixed[11];
uint64_t mtrr_deftype;
struct {
uint64_t base;
uint64_t mask;
} mtrr_var[8];
#ifdef USE_KQEMU
int kqemu_enabled;
int last_io_time;
@ -805,7 +830,7 @@ static inline int cpu_get_time_fast(void)
#define cpu_signal_handler cpu_x86_signal_handler
#define cpu_list x86_cpu_list
#define CPU_SAVE_VERSION 7
#define CPU_SAVE_VERSION 8
/* MMU modes definitions */
#define MMU_MODE0_SUFFIX _kernel

80
target-i386/op_helper.c
View File

@ -3050,6 +3050,46 @@ void helper_wrmsr(void)
env->kernelgsbase = val;
break;
#endif
case MSR_MTRRphysBase(0):
case MSR_MTRRphysBase(1):
case MSR_MTRRphysBase(2):
case MSR_MTRRphysBase(3):
case MSR_MTRRphysBase(4):
case MSR_MTRRphysBase(5):
case MSR_MTRRphysBase(6):
case MSR_MTRRphysBase(7):
env->mtrr_var[((uint32_t)ECX - MSR_MTRRphysBase(0)) / 2].base = val;
break;
case MSR_MTRRphysMask(0):
case MSR_MTRRphysMask(1):
case MSR_MTRRphysMask(2):
case MSR_MTRRphysMask(3):
case MSR_MTRRphysMask(4):
case MSR_MTRRphysMask(5):
case MSR_MTRRphysMask(6):
case MSR_MTRRphysMask(7):
env->mtrr_var[((uint32_t)ECX - MSR_MTRRphysMask(0)) / 2].mask = val;
break;
case MSR_MTRRfix64K_00000:
env->mtrr_fixed[(uint32_t)ECX - MSR_MTRRfix64K_00000] = val;
break;
case MSR_MTRRfix16K_80000:
case MSR_MTRRfix16K_A0000:
env->mtrr_fixed[(uint32_t)ECX - MSR_MTRRfix16K_80000 + 1] = val;
break;
case MSR_MTRRfix4K_C0000:
case MSR_MTRRfix4K_C8000:
case MSR_MTRRfix4K_D0000:
case MSR_MTRRfix4K_D8000:
case MSR_MTRRfix4K_E0000:
case MSR_MTRRfix4K_E8000:
case MSR_MTRRfix4K_F0000:
case MSR_MTRRfix4K_F8000:
env->mtrr_fixed[(uint32_t)ECX - MSR_MTRRfix4K_C0000 + 3] = val;
break;
case MSR_MTRRdefType:
env->mtrr_deftype = val;
break;
default:
/* XXX: exception ? */
break;
@ -3122,6 +3162,46 @@ void helper_rdmsr(void)
}
break;
#endif
case MSR_MTRRphysBase(0):
case MSR_MTRRphysBase(1):
case MSR_MTRRphysBase(2):
case MSR_MTRRphysBase(3):
case MSR_MTRRphysBase(4):
case MSR_MTRRphysBase(5):
case MSR_MTRRphysBase(6):
case MSR_MTRRphysBase(7):
val = env->mtrr_var[((uint32_t)ECX - MSR_MTRRphysBase(0)) / 2].base;
break;
case MSR_MTRRphysMask(0):
case MSR_MTRRphysMask(1):
case MSR_MTRRphysMask(2):
case MSR_MTRRphysMask(3):
case MSR_MTRRphysMask(4):
case MSR_MTRRphysMask(5):
case MSR_MTRRphysMask(6):
case MSR_MTRRphysMask(7):
val = env->mtrr_var[((uint32_t)ECX - MSR_MTRRphysMask(0)) / 2].mask;
break;
case MSR_MTRRfix64K_00000:
val = env->mtrr_fixed[0];
break;
case MSR_MTRRfix16K_80000:
case MSR_MTRRfix16K_A0000:
val = env->mtrr_fixed[(uint32_t)ECX - MSR_MTRRfix16K_80000 + 1];
break;
case MSR_MTRRfix4K_C0000:
case MSR_MTRRfix4K_C8000:
case MSR_MTRRfix4K_D0000:
case MSR_MTRRfix4K_D8000:
case MSR_MTRRfix4K_E0000:
case MSR_MTRRfix4K_E8000:
case MSR_MTRRfix4K_F0000:
case MSR_MTRRfix4K_F8000:
val = env->mtrr_fixed[(uint32_t)ECX - MSR_MTRRfix4K_C0000 + 3];
break;
case MSR_MTRRdefType:
val = env->mtrr_deftype;
break;
default:
/* XXX: exception ? */
val = 0;