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KVM: VMX: Drop unnecessary vmx_fb_clear_ctrl_available "cache"

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Now that KVM snapshots the host's MSR_IA32_ARCH_CAPABILITIES, drop the
similar snapshot/cache of whether or not KVM is allowed to manipulate
MSR_IA32_MCU_OPT_CTRL.FB_CLEAR_DIS.  The motivation for the cache was
presumably to avoid the RDMSR, e.g. boot_cpu_has_bug() is quite cheap, and
modifying the vCPU's MSR_IA32_ARCH_CAPABILITIES is an infrequent option
and a relatively slow path.

Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20230607004311.1420507-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2023-06-06 17:43:10 -07:00
parent a2fd5d02ba
commit 550ba57faa
1 changed files with 3 additions and 14 deletions
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17
arch/x86/kvm/vmx/vmx.c
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@ -237,9 +237,6 @@ static const struct {
#define L1D_CACHE_ORDER 4
static void *vmx_l1d_flush_pages;
/* Control for disabling CPU Fill buffer clear */
static bool __read_mostly vmx_fb_clear_ctrl_available;
static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf)
{
struct page *page;
@ -366,14 +363,6 @@ static int vmentry_l1d_flush_get(char *s, const struct kernel_param *kp)
return sysfs_emit(s, "%s\n", vmentry_l1d_param[l1tf_vmx_mitigation].option);
}
static void vmx_setup_fb_clear_ctrl(void)
{
if ((host_arch_capabilities & ARCH_CAP_FB_CLEAR_CTRL) &&
!boot_cpu_has_bug(X86_BUG_MDS) &&
!boot_cpu_has_bug(X86_BUG_TAA))
vmx_fb_clear_ctrl_available = true;
}
static __always_inline void vmx_disable_fb_clear(struct vcpu_vmx *vmx)
{
u64 msr;
@ -399,7 +388,9 @@ static __always_inline void vmx_enable_fb_clear(struct vcpu_vmx *vmx)
static void vmx_update_fb_clear_dis(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx)
{
vmx->disable_fb_clear = vmx_fb_clear_ctrl_available;
vmx->disable_fb_clear = (host_arch_capabilities & ARCH_CAP_FB_CLEAR_CTRL) &&
!boot_cpu_has_bug(X86_BUG_MDS) &&
!boot_cpu_has_bug(X86_BUG_TAA);
/*
* If guest will not execute VERW, there is no need to set FB_CLEAR_DIS
@ -8626,8 +8617,6 @@ static int __init vmx_init(void)
if (r)
goto err_l1d_flush;
vmx_setup_fb_clear_ctrl();
for_each_possible_cpu(cpu) {
INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));