[v2] target/i386: Added VGIF feature

Commit Message

Lara Lazier July 28, 2021, 11:37 a.m. UTC

VGIF allows STGI and CLGI to execute in guest mode and control virtual
interrupts in guest mode.
When the VGIF feature is enabled then:
 * executing STGI in the guest sets bit 9 of the VMCB offset 60h.
 * executing CLGI in the guest clears bit 9 of the VMCB offset 60h.

Signed-off-by: Lara Lazier <[e-mail]>
---
 target/i386/cpu.c                   |  3 ++-
 target/i386/svm.h                   |  6 ++++++
 target/i386/tcg/sysemu/svm_helper.c | 27 +++++++++++++++++++++++++--
 3 files changed, 33 insertions(+), 3 deletions(-)

Comments

Paolo Bonzini July 29, 2021, 7:59 a.m. UTC | #1

On 28/07/21 13:37, Lara Lazier wrote:
> +    if (virtual_gif_enabled(env, int_ctl) && likely(env->hflags & HF_GUEST_MASK)) {
> +        x86_stl_phys(cs, env->vm_vmcb + offsetof(struct vmcb, control.int_ctl),
> +                        int_ctl | V_GIF_MASK);
> +    } else {

I would put the HF_GUEST_MASK check in virtual_gif_enabled.

In fact, the more logical order for the three checks is:

- am I in guest mode? (if not, the VMCB and thus int_ctl is unused)

- is the CPUID bit set? (if not, bit 9 has no effect)

- is bit 9 of int_ctl set?

Thanks,

Paolo

Paolo Bonzini July 29, 2021, 8:01 a.m. UTC | #2

On 28/07/21 13:37, Lara Lazier wrote:
> +    uint32_t int_ctl = x86_ldl_phys(cs,
> +                       env->vm_vmcb + offsetof(struct vmcb, control.int_ctl));
> +    if (virtual_gif_enabled(env, int_ctl) && likely(env->hflags & HF_GUEST_MASK)) {
> +        x86_stl_phys(cs, env->vm_vmcb + offsetof(struct vmcb, control.int_ctl),
> +                        int_ctl & ~V_GIF_MASK);
> +    } else {

Sorry for the double reply.  env->vm_vmcb is not guaranteed to be valid 
if not in guest mode, so there are two possibilities.

1) Keep the HF_GUEST_MASK check directly in the helpers, but do it 
before x86_ldl_phys

2) Move x86_ldl_phys to virtual_gif_enabled, with a prototype like

bool virtual_gif_enabled(CPUX86State *env, uint32_t *int_ctl)

i.e. returning int_ctl from virtual_gif_enabled via pass-by-reference.

Thanks,

Paolo

Patch

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index edb97ebbbe..71d26cf1bd 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -631,7 +631,8 @@  void x86_cpu_vendor_words2str(char *dst, uint32_t vendor1,
 #define TCG_EXT3_FEATURES (CPUID_EXT3_LAHF_LM | CPUID_EXT3_SVM | \
           CPUID_EXT3_CR8LEG | CPUID_EXT3_ABM | CPUID_EXT3_SSE4A)
 #define TCG_EXT4_FEATURES 0
-#define TCG_SVM_FEATURES CPUID_SVM_NPT
+#define TCG_SVM_FEATURES (CPUID_SVM_NPT | CPUID_SVM_VGIF | \
+          CPUID_SVM_SVME_ADDR_CHK)
 #define TCG_KVM_FEATURES 0
 #define TCG_7_0_EBX_FEATURES (CPUID_7_0_EBX_SMEP | CPUID_7_0_EBX_SMAP | \
           CPUID_7_0_EBX_BMI1 | CPUID_7_0_EBX_BMI2 | CPUID_7_0_EBX_ADX | \
diff --git a/target/i386/svm.h b/target/i386/svm.h
index e54670ef12..dab2f90925 100644
--- a/target/i386/svm.h
+++ b/target/i386/svm.h
@@ -9,6 +9,12 @@ 
 #define V_IRQ_SHIFT 8
 #define V_IRQ_MASK (1 << V_IRQ_SHIFT)
 
+#define V_GIF_ENABLED_SHIFT 25
+#define V_GIF_ENABLED_MASK (1 << V_GIF_ENABLED_SHIFT)
+
+#define V_GIF_SHIFT 9
+#define V_GIF_MASK (1 << V_GIF_SHIFT)
+
 #define V_INTR_PRIO_SHIFT 16
 #define V_INTR_PRIO_MASK (0x0f << V_INTR_PRIO_SHIFT)
 
diff --git a/target/i386/tcg/sysemu/svm_helper.c b/target/i386/tcg/sysemu/svm_helper.c
index 7b80f7bc85..72ea7c9a08 100644
--- a/target/i386/tcg/sysemu/svm_helper.c
+++ b/target/i386/tcg/sysemu/svm_helper.c
@@ -120,6 +120,11 @@  static inline void svm_vmload_canonicalization(CPUX86State *env)
     env->segs[R_GS].base = (long) (env->segs[R_GS].base & mask);
 }
 
+static inline bool virtual_gif_enabled(CPUX86State *env, uint32_t int_ctl)
+{
+    return (int_ctl & V_GIF_ENABLED_MASK) && (env->features[FEAT_SVM] & CPUID_SVM_VGIF);
+}
+
 void helper_vmrun(CPUX86State *env, int aflag, int next_eip_addend)
 {
     CPUState *cs = env_cpu(env);
@@ -517,13 +522,31 @@  void helper_vmsave(CPUX86State *env, int aflag)
 void helper_stgi(CPUX86State *env)
 {
     cpu_svm_check_intercept_param(env, SVM_EXIT_STGI, 0, GETPC());
-    env->hflags2 |= HF2_GIF_MASK;
+
+    CPUState *cs = env_cpu(env);
+    uint32_t int_ctl = x86_ldl_phys(cs,
+                       env->vm_vmcb + offsetof(struct vmcb, control.int_ctl));
+    if (virtual_gif_enabled(env, int_ctl) && likely(env->hflags & HF_GUEST_MASK)) {
+        x86_stl_phys(cs, env->vm_vmcb + offsetof(struct vmcb, control.int_ctl),
+                        int_ctl | V_GIF_MASK);
+    } else {
+        env->hflags2 |= HF2_GIF_MASK;
+    }
 }
 
 void helper_clgi(CPUX86State *env)
 {
     cpu_svm_check_intercept_param(env, SVM_EXIT_CLGI, 0, GETPC());
-    env->hflags2 &= ~HF2_GIF_MASK;
+
+    CPUState *cs = env_cpu(env);
+    uint32_t int_ctl = x86_ldl_phys(cs,
+                       env->vm_vmcb + offsetof(struct vmcb, control.int_ctl));
+    if (virtual_gif_enabled(env, int_ctl) && likely(env->hflags & HF_GUEST_MASK)) {
+        x86_stl_phys(cs, env->vm_vmcb + offsetof(struct vmcb, control.int_ctl),
+                        int_ctl & ~V_GIF_MASK);
+    } else {
+        env->hflags2 &= ~HF2_GIF_MASK;
+    }
 }
 
 bool cpu_svm_has_intercept(CPUX86State *env, uint32_t type)