KVM: VMX: Track CPU's MSR_IA32_VMX_BASIC as a single 64-bit value

Track the "basic" capabilities VMX MSR as a single u64 in vmcs_config
instead of splitting it across three fields, that obviously don't combine
into a single 64-bit value, so that KVM can use the macros that define MSR
bits using their absolute position.  Replace all open coded shifts and
masks, many of which are relative to the "high" half, with the appropriate
macro.

Opportunistically use VMX_BASIC_32BIT_PHYS_ADDR_ONLY instead of an open
coded equivalent, and clean up the related comment to not reference a
specific SDM section (to the surprise of no one, the comment is stale).

No functional change intended (though obviously the code generation will
be quite different).

Cc: Shan Kang <shan.kang@intel.com>
Cc: Kai Huang <kai.huang@intel.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
[sean: split to separate patch, write changelog]
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20240605231918.2915961-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 81b986e501a937e8ba0814231d80eec628b91ec7..90963b14afaad7c6ab2f22d97f90ea75b566d13f 100644 (file)
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -152,6 +152,11 @@ static inline u32 vmx_basic_vmcs_size(u64 vmx_basic)
        return (vmx_basic & GENMASK_ULL(44, 32)) >> 32;
 }
 
+static inline u32 vmx_basic_vmcs_mem_type(u64 vmx_basic)
+{
+       return (vmx_basic & GENMASK_ULL(53, 50)) >> 50;
+}
+
 static inline int vmx_misc_preemption_timer_rate(u64 vmx_misc)
 {
        return vmx_misc & VMX_MISC_PREEMPTION_TIMER_RATE_MASK;

diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 41a4533f9989748c9226255e6aa7c043ced40ecc..86ce8bb96bed7bd5209893aa89b4c581c1f6a678 100644 (file)
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -54,9 +54,7 @@ struct nested_vmx_msrs {
 };
 
 struct vmcs_config {
-       int size;
-       u32 basic_cap;
-       u32 revision_id;
+       u64 basic;
        u32 pin_based_exec_ctrl;
        u32 cpu_based_exec_ctrl;
        u32 cpu_based_2nd_exec_ctrl;
@@ -76,7 +74,7 @@ extern struct vmx_capability vmx_capability __ro_after_init;
 
 static inline bool cpu_has_vmx_basic_inout(void)
 {
-       return  (((u64)vmcs_config.basic_cap << 32) & VMX_BASIC_INOUT);
+       return  vmcs_config.basic & VMX_BASIC_INOUT;
 }
 
 static inline bool cpu_has_virtual_nmis(void)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a4d077db04cf6e3ae2b7c091a121c22852349974..5cbd86c4386b07ba98432fe451ef9e20c8b5c290 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2605,13 +2605,13 @@ static u64 adjust_vmx_controls64(u64 ctl_opt, u32 msr)
 static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
                             struct vmx_capability *vmx_cap)
 {
-       u32 vmx_msr_low, vmx_msr_high;
        u32 _pin_based_exec_control = 0;
        u32 _cpu_based_exec_control = 0;
        u32 _cpu_based_2nd_exec_control = 0;
        u64 _cpu_based_3rd_exec_control = 0;
        u32 _vmexit_control = 0;
        u32 _vmentry_control = 0;
+       u64 basic_msr;
        u64 misc_msr;
        int i;
 
@@ -2734,29 +2734,29 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
                _vmexit_control &= ~x_ctrl;
        }
 
-       rdmsr(MSR_IA32_VMX_BASIC, vmx_msr_low, vmx_msr_high);
+       rdmsrl(MSR_IA32_VMX_BASIC, basic_msr);
 
        /* IA-32 SDM Vol 3B: VMCS size is never greater than 4kB. */
-       if ((vmx_msr_high & 0x1fff) > PAGE_SIZE)
+       if (vmx_basic_vmcs_size(basic_msr) > PAGE_SIZE)
                return -EIO;
 
 #ifdef CONFIG_X86_64
-       /* IA-32 SDM Vol 3B: 64-bit CPUs always have VMX_BASIC_MSR[48]==0. */
-       if (vmx_msr_high & (1u<<16))
+       /*
+        * KVM expects to be able to shove all legal physical addresses into
+        * VMCS fields for 64-bit kernels, and per the SDM, "This bit is always
+        * 0 for processors that support Intel 64 architecture".
+        */
+       if (basic_msr & VMX_BASIC_32BIT_PHYS_ADDR_ONLY)
                return -EIO;
 #endif
 
        /* Require Write-Back (WB) memory type for VMCS accesses. */
-       if (((vmx_msr_high >> 18) & 15) != X86_MEMTYPE_WB)
+       if (vmx_basic_vmcs_mem_type(basic_msr) != X86_MEMTYPE_WB)
                return -EIO;
 
        rdmsrl(MSR_IA32_VMX_MISC, misc_msr);
 
-       vmcs_conf->size = vmx_msr_high & 0x1fff;
-       vmcs_conf->basic_cap = vmx_msr_high & ~0x1fff;
-
-       vmcs_conf->revision_id = vmx_msr_low;
-
+       vmcs_conf->basic = basic_msr;
        vmcs_conf->pin_based_exec_ctrl = _pin_based_exec_control;
        vmcs_conf->cpu_based_exec_ctrl = _cpu_based_exec_control;
        vmcs_conf->cpu_based_2nd_exec_ctrl = _cpu_based_2nd_exec_control;
@@ -2903,13 +2903,13 @@ struct vmcs *alloc_vmcs_cpu(bool shadow, int cpu, gfp_t flags)
        if (!pages)
                return NULL;
        vmcs = page_address(pages);
-       memset(vmcs, 0, vmcs_config.size);
+       memset(vmcs, 0, vmx_basic_vmcs_size(vmcs_config.basic));
 
        /* KVM supports Enlightened VMCS v1 only */
        if (kvm_is_using_evmcs())
                vmcs->hdr.revision_id = KVM_EVMCS_VERSION;
        else
-               vmcs->hdr.revision_id = vmcs_config.revision_id;
+               vmcs->hdr.revision_id = vmx_basic_vmcs_revision_id(vmcs_config.basic);
 
        if (shadow)
                vmcs->hdr.shadow_vmcs = 1;
@@ -3002,7 +3002,7 @@ static __init int alloc_kvm_area(void)
                 * physical CPU.
                 */
                if (kvm_is_using_evmcs())
-                       vmcs->hdr.revision_id = vmcs_config.revision_id;
+                       vmcs->hdr.revision_id = vmx_basic_vmcs_revision_id(vmcs_config.basic);
 
                per_cpu(vmxarea, cpu) = vmcs;
        }