drm/i915/gvt: introduced failsafe mode into vgpu

New failsafe mode is introduced, when we detect guest not supporting
GVT-g.
In failsafe mode, we will ignore all the MMIO and cfg space read/write
from guest.

This patch can fix the issue that when guest kernel or graphics driver
version is too low, there will be a lot of kernel traces in host.

V5: rebased onto latest gvt-staging
V4: changed coding style by Zhenyu and Ping's advice
V3: modified coding style and error messages according to Zhenyu's comment
V2: 1) implemented MMIO/GTT/WP pages read/write logic; 2) used a unified
function to enter failsafe mode

Signed-off-by: Min He <min.he@intel.com>
Signed-off-by: Pei Zhang <pei.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/gvt/cfg_space.c b/drivers/gpu/drm/i915/gvt/cfg_space.c
index 4a6a2ed..a77e050 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/cfg_space.c
+++ b/drivers/gpu/drm/i915/gvt/cfg_space.c
@@ -237,6 +237,9 @@ int intel_vgpu_emulate_cfg_write(struct intel_vgpu *vgpu, unsigned int offset,
 {
        int ret;
 
+       if (vgpu->failsafe)
+               return 0;
+
        if (WARN_ON(bytes > 4))
                return -EINVAL;
 

diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
index 5ee6600..48ef077 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/gvt.h
+++ b/drivers/gpu/drm/i915/gvt/gvt.h
@@ -143,6 +143,8 @@ struct intel_vgpu {
        int id;
        unsigned long handle; /* vGPU handle used by hypervisor MPT modules */
        bool active;
+       bool pv_notified;
+       bool failsafe;
        bool resetting;
        void *sched_data;
 
@@ -449,6 +451,10 @@ struct intel_gvt_ops {
 };
 
 
+enum {
+       GVT_FAILSAFE_UNSUPPORTED_GUEST,
+};
+
 #include "mpt.h"
 
 #endif

diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
index 1d45062..6f098bb 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/handlers.c
+++ b/drivers/gpu/drm/i915/gvt/handlers.c
@@ -150,10 +150,34 @@ static int render_mmio_to_ring_id(struct intel_gvt *gvt, unsigned int reg)
 #define fence_num_to_offset(num) \
        (num * 8 + i915_mmio_reg_offset(FENCE_REG_GEN6_LO(0)))
 
+
+static void enter_failsafe_mode(struct intel_vgpu *vgpu, int reason)
+{
+       switch (reason) {
+       case GVT_FAILSAFE_UNSUPPORTED_GUEST:
+               pr_err("Detected your guest driver doesn't support GVT-g.\n");
+               break;
+       default:
+               break;
+       }
+       pr_err("Now vgpu %d will enter failsafe mode.\n", vgpu->id);
+       vgpu->failsafe = true;
+}
+
 static int sanitize_fence_mmio_access(struct intel_vgpu *vgpu,
                unsigned int fence_num, void *p_data, unsigned int bytes)
 {
        if (fence_num >= vgpu_fence_sz(vgpu)) {
+
+               /* When guest access oob fence regs without access
+                * pv_info first, we treat guest not supporting GVT,
+                * and we will let vgpu enter failsafe mode.
+                */
+               if (!vgpu->pv_notified) {
+                       enter_failsafe_mode(vgpu,
+                                       GVT_FAILSAFE_UNSUPPORTED_GUEST);
+                       return -EINVAL;
+               }
                gvt_err("vgpu%d: found oob fence register access\n",
                                vgpu->id);
                gvt_err("vgpu%d: total fence num %d access fence num %d\n",
@@ -1001,6 +1025,7 @@ static int pvinfo_mmio_read(struct intel_vgpu *vgpu, unsigned int offset,
        if (invalid_read)
                gvt_err("invalid pvinfo read: [%x:%x] = %x\n",
                                offset, bytes, *(u32 *)p_data);
+       vgpu->pv_notified = true;
        return 0;
 }
 
@@ -1318,6 +1343,17 @@ static int ring_mode_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
        bool enable_execlist;
 
        write_vreg(vgpu, offset, p_data, bytes);
+
+       /* when PPGTT mode enabled, we will check if guest has called
+        * pvinfo, if not, we will treat this guest as non-gvtg-aware
+        * guest, and stop emulating its cfg space, mmio, gtt, etc.
+        */
+       if (((data & _MASKED_BIT_ENABLE(GFX_PPGTT_ENABLE)) ||
+                       (data & _MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE)))
+                       && !vgpu->pv_notified) {
+               enter_failsafe_mode(vgpu, GVT_FAILSAFE_UNSUPPORTED_GUEST);
+               return 0;
+       }
        if ((data & _MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE))
                        || (data & _MASKED_BIT_DISABLE(GFX_RUN_LIST_ENABLE))) {
                enable_execlist = !!(data & GFX_RUN_LIST_ENABLE);

diff --git a/drivers/gpu/drm/i915/gvt/mmio.c b/drivers/gpu/drm/i915/gvt/mmio.c
index 4df078b..b2d72da 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/mmio.c
+++ b/drivers/gpu/drm/i915/gvt/mmio.c
@@ -57,6 +57,58 @@ int intel_vgpu_gpa_to_mmio_offset(struct intel_vgpu *vgpu, u64 gpa)
        (reg >= gvt->device_info.gtt_start_offset \
         && reg < gvt->device_info.gtt_start_offset + gvt_ggtt_sz(gvt))
 
+static void failsafe_emulate_mmio_rw(struct intel_vgpu *vgpu, uint64_t pa,
+               void *p_data, unsigned int bytes, bool read)
+{
+       struct intel_gvt *gvt = NULL;
+       void *pt = NULL;
+       unsigned int offset = 0;
+
+       if (!vgpu || !p_data)
+               return;
+
+       gvt = vgpu->gvt;
+       mutex_lock(&gvt->lock);
+       offset = intel_vgpu_gpa_to_mmio_offset(vgpu, pa);
+       if (reg_is_mmio(gvt, offset)) {
+               if (read)
+                       intel_vgpu_default_mmio_read(vgpu, offset, p_data,
+                                       bytes);
+               else
+                       intel_vgpu_default_mmio_write(vgpu, offset, p_data,
+                                       bytes);
+       } else if (reg_is_gtt(gvt, offset) &&
+                       vgpu->gtt.ggtt_mm->virtual_page_table) {
+               offset -= gvt->device_info.gtt_start_offset;
+               pt = vgpu->gtt.ggtt_mm->virtual_page_table + offset;
+               if (read)
+                       memcpy(p_data, pt, bytes);
+               else
+                       memcpy(pt, p_data, bytes);
+
+       } else if (atomic_read(&vgpu->gtt.n_write_protected_guest_page)) {
+               struct intel_vgpu_guest_page *gp;
+
+               /* Since we enter the failsafe mode early during guest boot,
+                * guest may not have chance to set up its ppgtt table, so
+                * there should not be any wp pages for guest. Keep the wp
+                * related code here in case we need to handle it in furture.
+                */
+               gp = intel_vgpu_find_guest_page(vgpu, pa >> PAGE_SHIFT);
+               if (gp) {
+                       /* remove write protection to prevent furture traps */
+                       intel_vgpu_clean_guest_page(vgpu, gp);
+                       if (read)
+                               intel_gvt_hypervisor_read_gpa(vgpu, pa,
+                                               p_data, bytes);
+                       else
+                               intel_gvt_hypervisor_write_gpa(vgpu, pa,
+                                               p_data, bytes);
+               }
+       }
+       mutex_unlock(&gvt->lock);
+}
+
 /**
  * intel_vgpu_emulate_mmio_read - emulate MMIO read
  * @vgpu: a vGPU
@@ -75,6 +127,11 @@ int intel_vgpu_emulate_mmio_read(struct intel_vgpu *vgpu, uint64_t pa,
        unsigned int offset = 0;
        int ret = -EINVAL;
 
+
+       if (vgpu->failsafe) {
+               failsafe_emulate_mmio_rw(vgpu, pa, p_data, bytes, true);
+               return 0;
+       }
        mutex_lock(&gvt->lock);
 
        if (atomic_read(&vgpu->gtt.n_write_protected_guest_page)) {
@@ -188,6 +245,11 @@ int intel_vgpu_emulate_mmio_write(struct intel_vgpu *vgpu, uint64_t pa,
        u32 old_vreg = 0, old_sreg = 0;
        int ret = -EINVAL;
 
+       if (vgpu->failsafe) {
+               failsafe_emulate_mmio_rw(vgpu, pa, p_data, bytes, false);
+               return 0;
+       }
+
        mutex_lock(&gvt->lock);
 
        if (atomic_read(&vgpu->gtt.n_write_protected_guest_page)) {

diff --git a/drivers/gpu/drm/i915/gvt/vgpu.c b/drivers/gpu/drm/i915/gvt/vgpu.c
index 95a97aa..dcfcce1 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/vgpu.c
+++ b/drivers/gpu/drm/i915/gvt/vgpu.c
@@ -387,8 +387,12 @@ void intel_gvt_reset_vgpu_locked(struct intel_vgpu *vgpu, bool dmlr,
                populate_pvinfo_page(vgpu);
                intel_vgpu_reset_display(vgpu);
 
-               if (dmlr)
+               if (dmlr) {
                        intel_vgpu_reset_cfg_space(vgpu);
+                       /* only reset the failsafe mode when dmlr reset */
+                       vgpu->failsafe = false;
+                       vgpu->pv_notified = false;
+               }
        }
 
        vgpu->resetting = false;