[xen master] x86/msr: Split MSR_SPEC_CTRL handling

[patchbot@xxxxxxx]

commit 6536688439dbca1d08fd6db5be29c39e3917fb2f
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Wed Jan 12 13:52:47 2022 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Jan 20 16:32:11 2022 +0000

    x86/msr: Split MSR_SPEC_CTRL handling
    
    In order to fix a VT-x bug, and support MSR_SPEC_CTRL on AMD, move
    MSR_SPEC_CTRL handling into the new {pv,hvm}_{get,set}_reg() infrastructure.
    
    Duplicate the msrs->spec_ctrl.raw accesses in the PV and VT-x paths for now.
    The SVM path is currently unreachable because of the CPUID policy.
    
    No functional change.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmx.c |  7 +++++++
 xen/arch/x86/msr.c         | 22 +++++++++++++++++-----
 xen/arch/x86/pv/emulate.c  |  9 +++++++++
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 6b0455a1cf..833a4af6f0 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2405,6 +2405,9 @@ static uint64_t vmx_get_reg(struct vcpu *v, unsigned int 
reg)
 
     switch ( reg )
     {
+    case MSR_SPEC_CTRL:
+        return v->arch.msrs->spec_ctrl.raw;
+
     default:
         printk(XENLOG_G_ERR "%s(%pv, 0x%08x) Bad register\n",
                __func__, v, reg);
@@ -2419,6 +2422,10 @@ static void vmx_set_reg(struct vcpu *v, unsigned int 
reg, uint64_t val)
 
     switch ( reg )
     {
+    case MSR_SPEC_CTRL:
+        v->arch.msrs->spec_ctrl.raw = val;
+        break;
+
     default:
         printk(XENLOG_G_ERR "%s(%pv, 0x%08x, 0x%016"PRIx64") Bad register\n",
                __func__, v, reg, val);
diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index b834456c7b..71cbfa8ee3 100644
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -28,6 +28,7 @@
 #include <asm/hvm/nestedhvm.h>
 #include <asm/hvm/viridian.h>
 #include <asm/msr.h>
+#include <asm/pv/domain.h>
 #include <asm/setup.h>
 
 #include <public/hvm/params.h>
@@ -265,8 +266,7 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t *val)
     case MSR_SPEC_CTRL:
         if ( !cp->feat.ibrsb )
             goto gp_fault;
-        *val = msrs->spec_ctrl.raw;
-        break;
+        goto get_reg;
 
     case MSR_INTEL_PLATFORM_INFO:
         *val = mp->platform_info.raw;
@@ -424,6 +424,13 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t 
*val)
 
     return ret;
 
+ get_reg: /* Delegate register access to per-vm-type logic. */
+    if ( is_pv_domain(d) )
+        *val = pv_get_reg(v, msr);
+    else
+        *val = hvm_get_reg(v, msr);
+    return X86EMUL_OKAY;
+
  gp_fault:
     return X86EMUL_EXCEPTION;
 }
@@ -513,9 +520,7 @@ int guest_wrmsr(struct vcpu *v, uint32_t msr, uint64_t val)
 
         if ( val & rsvd )
             goto gp_fault; /* Rsvd bit set? */
-
-        msrs->spec_ctrl.raw = val;
-        break;
+        goto set_reg;
 
     case MSR_PRED_CMD:
         if ( !cp->feat.ibrsb && !cp->extd.ibpb )
@@ -663,6 +668,13 @@ int guest_wrmsr(struct vcpu *v, uint32_t msr, uint64_t val)
 
     return ret;
 
+ set_reg: /* Delegate register access to per-vm-type logic. */
+    if ( is_pv_domain(d) )
+        pv_set_reg(v, msr, val);
+    else
+        hvm_set_reg(v, msr, val);
+    return X86EMUL_OKAY;
+
  gp_fault:
     return X86EMUL_EXCEPTION;
 }
diff --git a/xen/arch/x86/pv/emulate.c b/xen/arch/x86/pv/emulate.c
index ae049b60f2..0a7907ec5e 100644
--- a/xen/arch/x86/pv/emulate.c
+++ b/xen/arch/x86/pv/emulate.c
@@ -92,12 +92,16 @@ void pv_emul_instruction_done(struct cpu_user_regs *regs, 
unsigned long rip)
 
 uint64_t pv_get_reg(struct vcpu *v, unsigned int reg)
 {
+    const struct vcpu_msrs *msrs = v->arch.msrs;
     struct domain *d = v->domain;
 
     ASSERT(v == current || !vcpu_runnable(v));
 
     switch ( reg )
     {
+    case MSR_SPEC_CTRL:
+        return msrs->spec_ctrl.raw;
+
     default:
         printk(XENLOG_G_ERR "%s(%pv, 0x%08x) Bad register\n",
                __func__, v, reg);
@@ -108,12 +112,17 @@ uint64_t pv_get_reg(struct vcpu *v, unsigned int reg)
 
 void pv_set_reg(struct vcpu *v, unsigned int reg, uint64_t val)
 {
+    struct vcpu_msrs *msrs = v->arch.msrs;
     struct domain *d = v->domain;
 
     ASSERT(v == current || !vcpu_runnable(v));
 
     switch ( reg )
     {
+    case MSR_SPEC_CTRL:
+        msrs->spec_ctrl.raw = val;
+        break;
+
     default:
         printk(XENLOG_G_ERR "%s(%pv, 0x%08x, 0x%016"PRIx64") Bad register\n",
                __func__, v, reg, val);
--
generated by git-patchbot for /home/xen/git/xen.git#master