From fcc35e7ccaed771790940524f3b0eef7aebfc9b1 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Fri, 8 Jul 2016 16:01:38 +0100 Subject: [PATCH] target-i386: Fill high bits of mtrr mask Fill the bits between 51..number-of-physical-address-bits in the MTRR_PHYSMASKn variable range mtrr masks so that they're consistent in the migration stream irrespective of the physical address space of the source VM in a migration. Signed-off-by: Dr. David Alan Gilbert Suggested-by: Paolo Bonzini Reviewed-by: Eduardo Habkost Signed-off-by: Eduardo Habkost --- include/hw/i386/pc.h | 5 +++++ target-i386/cpu.c | 1 + target-i386/cpu.h | 3 +++ target-i386/kvm.c | 28 +++++++++++++++++++++++++++- 4 files changed, 36 insertions(+), 1 deletion(-) diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index e38c95a4da..47411cbde4 100644 --- a/include/hw/i386/pc.h +++ b/include/hw/i386/pc.h @@ -377,6 +377,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *); .driver = "vmxnet3",\ .property = "romfile",\ .value = "",\ + },\ + {\ + .driver = TYPE_X86_CPU,\ + .property = "fill-mtrr-mask",\ + .value = "off",\ }, #define PC_COMPAT_2_5 \ diff --git a/target-i386/cpu.c b/target-i386/cpu.c index 669180e3fe..5ac7e975ad 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -3328,6 +3328,7 @@ static Property x86_cpu_properties[] = { DEFINE_PROP_BOOL("enforce", X86CPU, enforce_cpuid, false), DEFINE_PROP_BOOL("kvm", X86CPU, expose_kvm, true), DEFINE_PROP_UINT32("phys-bits", X86CPU, phys_bits, 0), + DEFINE_PROP_BOOL("fill-mtrr-mask", X86CPU, fill_mtrr_mask, true), DEFINE_PROP_UINT32("level", X86CPU, env.cpuid_level, 0), DEFINE_PROP_UINT32("xlevel", X86CPU, env.cpuid_xlevel, 0), DEFINE_PROP_UINT32("xlevel2", X86CPU, env.cpuid_xlevel2, 0), diff --git a/target-i386/cpu.h b/target-i386/cpu.h index b2ddcb8085..b2ab8bf4be 100644 --- a/target-i386/cpu.h +++ b/target-i386/cpu.h @@ -1198,6 +1198,9 @@ struct X86CPU { /* Compatibility bits for old machine types: */ bool enable_cpuid_0xb; + /* if true fill the top bits of the MTRR_PHYSMASKn variable range */ + bool fill_mtrr_mask; + /* Number of physical address bits supported */ uint32_t phys_bits; diff --git a/target-i386/kvm.c b/target-i386/kvm.c index 2f1cc62795..df28dd254a 100644 --- a/target-i386/kvm.c +++ b/target-i386/kvm.c @@ -1977,6 +1977,7 @@ static int kvm_get_msrs(X86CPU *cpu) CPUX86State *env = &cpu->env; struct kvm_msr_entry *msrs = cpu->kvm_msr_buf->entries; int ret, i; + uint64_t mtrr_top_bits; kvm_msr_buf_reset(cpu); @@ -2129,6 +2130,30 @@ static int kvm_get_msrs(X86CPU *cpu) } assert(ret == cpu->kvm_msr_buf->nmsrs); + /* + * MTRR masks: Each mask consists of 5 parts + * a 10..0: must be zero + * b 11 : valid bit + * c n-1.12: actual mask bits + * d 51..n: reserved must be zero + * e 63.52: reserved must be zero + * + * 'n' is the number of physical bits supported by the CPU and is + * apparently always <= 52. We know our 'n' but don't know what + * the destinations 'n' is; it might be smaller, in which case + * it masks (c) on loading. It might be larger, in which case + * we fill 'd' so that d..c is consistent irrespetive of the 'n' + * we're migrating to. + */ + + if (cpu->fill_mtrr_mask) { + QEMU_BUILD_BUG_ON(TARGET_PHYS_ADDR_SPACE_BITS > 52); + assert(cpu->phys_bits <= TARGET_PHYS_ADDR_SPACE_BITS); + mtrr_top_bits = MAKE_64BIT_MASK(cpu->phys_bits, 52 - cpu->phys_bits); + } else { + mtrr_top_bits = 0; + } + for (i = 0; i < ret; i++) { uint32_t index = msrs[i].index; switch (index) { @@ -2327,7 +2352,8 @@ static int kvm_get_msrs(X86CPU *cpu) break; case MSR_MTRRphysBase(0) ... MSR_MTRRphysMask(MSR_MTRRcap_VCNT - 1): if (index & 1) { - env->mtrr_var[MSR_MTRRphysIndex(index)].mask = msrs[i].data; + env->mtrr_var[MSR_MTRRphysIndex(index)].mask = msrs[i].data | + mtrr_top_bits; } else { env->mtrr_var[MSR_MTRRphysIndex(index)].base = msrs[i].data; } -- 2.39.2