Commit bca06b85 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

Revert "KVM: VMX: Save HOST_CR3 in vmx_set_host_fs_gs()" 



Undo a nested VMX fix as a step toward reverting the commit it fixed,
15ad9762 ("KVM: VMX: Save HOST_CR3 in vmx_prepare_switch_to_guest()"),
as the underlying premise that "host CR3 in the vcpu thread can only be
changed when scheduling" is wrong.

This reverts commit a9f2705e.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20220224191917.3508476-2-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e910a53f

arch/x86/kvm/vmx/nested.c

+1 −2
Original line number Diff line number Diff line
@@ -246,8 +246,7 @@ static void vmx_sync_vmcs_host_state(struct vcpu_vmx *vmx, 
	src = &prev->host_state;

	dest = &vmx->loaded_vmcs->host_state;



	vmx_set_vmcs_host_state(dest, src->cr3, src->fs_sel, src->gs_sel,

				src->fs_base, src->gs_base);

	vmx_set_host_fs_gs(dest, src->fs_sel, src->gs_sel, src->fs_base, src->gs_base);

	dest->ldt_sel = src->ldt_sel;

#ifdef CONFIG_X86_64

	dest->ds_sel = src->ds_sel;

arch/x86/kvm/vmx/vmx.c

+11 −9
Original line number Diff line number Diff line
@@ -1080,14 +1080,9 @@ static void pt_guest_exit(struct vcpu_vmx *vmx) 
		wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl);

}



void vmx_set_vmcs_host_state(struct vmcs_host_state *host, unsigned long cr3,

			     u16 fs_sel, u16 gs_sel,

void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel,

			unsigned long fs_base, unsigned long gs_base)

{

	if (unlikely(cr3 != host->cr3)) {

		vmcs_writel(HOST_CR3, cr3);

		host->cr3 = cr3;

	}

	if (unlikely(fs_sel != host->fs_sel)) {

		if (!(fs_sel & 7))

			vmcs_write16(HOST_FS_SELECTOR, fs_sel);
@@ -1119,6 +1114,7 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) 
#ifdef CONFIG_X86_64

	int cpu = raw_smp_processor_id();

#endif

	unsigned long cr3;

	unsigned long fs_base, gs_base;

	u16 fs_sel, gs_sel;

	int i;
@@ -1182,8 +1178,14 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) 
	gs_base = segment_base(gs_sel);

#endif



	vmx_set_vmcs_host_state(host_state, __get_current_cr3_fast(),

				fs_sel, gs_sel, fs_base, gs_base);

	vmx_set_host_fs_gs(host_state, fs_sel, gs_sel, fs_base, gs_base);



	/* Host CR3 including its PCID is stable when guest state is loaded. */

	cr3 = __get_current_cr3_fast();

	if (unlikely(cr3 != host_state->cr3)) {

		vmcs_writel(HOST_CR3, cr3);

		host_state->cr3 = cr3;

	}



	vmx->guest_state_loaded = true;

}

arch/x86/kvm/vmx/vmx.h

+2 −3
Original line number Diff line number Diff line
@@ -374,8 +374,7 @@ int allocate_vpid(void); 
void free_vpid(int vpid);

void vmx_set_constant_host_state(struct vcpu_vmx *vmx);

void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu);

void vmx_set_vmcs_host_state(struct vmcs_host_state *host, unsigned long cr3,

			     u16 fs_sel, u16 gs_sel,

void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel,

			unsigned long fs_base, unsigned long gs_base);

int vmx_get_cpl(struct kvm_vcpu *vcpu);

bool vmx_emulation_required(struct kvm_vcpu *vcpu);