[Qemu-devel] [PATCH 4/8] target-i386: preserve FPU and MSR state on INIT

[Paolo Bonzini]

Most MSRs, plus the FPU, MMX, MXCSR, XMM and YMM registers should not
be zeroed on INIT (Table 9-1 in the Intel SDM).  Copy them out of
CPUX86State and back in, instead of special casing env->pat.

The relevant fields are already consecutive except PAT and SMBASE.
However:

- KVM and Hyper-V MSRs should be reset because they include memory
locations written by the hypervisor.  These MSRs are moved together
at the end of the preserved area.

- SVM state can be moved out of the way since it is written by VMRUN.

Cc: Andreas Färber <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
 target-i386/cpu.c    |  3 +--
 target-i386/cpu.h    | 42 ++++++++++++++++++++++++++----------------
 target-i386/helper.c | 10 ++++++++--
 3 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 78c1573..c14bd12 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -2410,8 +2410,7 @@ static void x86_cpu_reset(CPUState *s)
 
     xcc->parent_reset(s);
 
-
-    memset(env, 0, offsetof(CPUX86State, pat));
+    memset(env, 0, offsetof(CPUX86State, cpuid_level));
 
     tlb_flush(s, 1);
 
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index e2244e9..c205058 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -801,6 +801,9 @@ typedef struct CPUX86State {
     BNDCSReg bndcs_regs;
     uint64_t msr_bndcfgs;
 
+    /* Beginning of state preserved by INIT (dummy marker).  */
+    struct {} start_init_save;
+
     /* FPU state */
     unsigned int fpstt; /* top of stack index */
     uint16_t fpus;
@@ -833,15 +836,6 @@ typedef struct CPUX86State {
     uint64_t star;
 
     uint64_t vm_hsave;
-    uint64_t vm_vmcb;
-    uint64_t tsc_offset;
-    uint64_t intercept;
-    uint16_t intercept_cr_read;
-    uint16_t intercept_cr_write;
-    uint16_t intercept_dr_read;
-    uint16_t intercept_dr_write;
-    uint32_t intercept_exceptions;
-    uint8_t v_tpr;
 
 #ifdef TARGET_X86_64
     target_ulong lstar;
@@ -849,11 +843,6 @@ typedef struct CPUX86State {
     target_ulong fmask;
     target_ulong kernelgsbase;
 #endif
-    uint64_t system_time_msr;
-    uint64_t wall_clock_msr;
-    uint64_t steal_time_msr;
-    uint64_t async_pf_en_msr;
-    uint64_t pv_eoi_en_msr;
 
     uint64_t tsc;
     uint64_t tsc_adjust;
@@ -870,6 +859,19 @@ typedef struct CPUX86State {
     uint64_t msr_fixed_counters[MAX_FIXED_COUNTERS];
     uint64_t msr_gp_counters[MAX_GP_COUNTERS];
     uint64_t msr_gp_evtsel[MAX_GP_COUNTERS];
+
+    uint64_t pat;
+    uint32_t smbase;
+
+    /* End of state preserved by INIT (dummy marker).  */
+    struct {} end_init_save;
+
+    uint64_t system_time_msr;
+    uint64_t wall_clock_msr;
+    uint64_t steal_time_msr;
+    uint64_t async_pf_en_msr;
+    uint64_t pv_eoi_en_msr;
+
     uint64_t msr_hv_hypercall;
     uint64_t msr_hv_guest_os_id;
     uint64_t msr_hv_vapic;
@@ -884,9 +886,18 @@ typedef struct CPUX86State {
         struct CPUBreakpoint *cpu_breakpoint[4];
         struct CPUWatchpoint *cpu_watchpoint[4];
     }; /* break/watchpoints for dr[0..3] */
-    uint32_t smbase;
     int old_exception;  /* exception in flight */
 
+    uint64_t vm_vmcb;
+    uint64_t tsc_offset;
+    uint64_t intercept;
+    uint16_t intercept_cr_read;
+    uint16_t intercept_cr_write;
+    uint16_t intercept_dr_read;
+    uint16_t intercept_dr_write;
+    uint32_t intercept_exceptions;
+    uint8_t v_tpr;
+
     /* KVM states, automatically cleared on reset */
     uint8_t nmi_injected;
     uint8_t nmi_pending;
@@ -894,7 +905,6 @@ typedef struct CPUX86State {
     CPU_COMMON
 
     /* Fields from here on are preserved across CPU reset. */
-    uint64_t pat;
 
     /* processor features (e.g. for CPUID insn) */
     uint32_t cpuid_level;
diff --git a/target-i386/helper.c b/target-i386/helper.c
index 27b3582..46d20e4 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -1330,12 +1330,18 @@ void do_cpu_init(X86CPU *cpu)
 {
     CPUState *cs = CPU(cpu);
     CPUX86State *env = &cpu->env;
+    CPUX86State *save = g_new(CPUX86State, 1);
     int sipi = cs->interrupt_request & CPU_INTERRUPT_SIPI;
-    uint64_t pat = env->pat;
+
+    *save = *env;
 
     cpu_reset(cs);
     cs->interrupt_request = sipi;
-    env->pat = pat;
+    memcpy(&env->start_init_save, &save->start_init_save,
+           offsetof(CPUX86State, end_init_save) -
+           offsetof(CPUX86State, start_init_save));
+    g_free(save);
+
     if (kvm_enabled()) {
         kvm_arch_do_init_vcpu(cpu);
     }
-- 
1.8.3.1