x86/tss: Fix and move VMX BUILD_BUG_ON() (6b546e1c) · Commits · 戴 / test

The BUILD_BUG_ON(IO_BITMAP_OFFSET - 1 == 0x67) in the VMX code is bogus in two aspects: 1) This wants to be in generic x86 code simply to catch issues even when VMX is disabled in Kconfig. 2) The IO_BITMAP_OFFSET is not the right thing to check because it makes asssumptions about the layout of tss_struct. Nothing requires that the I/O bitmap is placed right after x86_tss, which is the hardware mandated tss structure. It pointlessly makes restrictions on the struct tss_struct layout. The proper thing to check is: - Offset of x86_tss in tss_struct is 0 - Size of x86_tss == 0x68 Move it to the other build time TSS checks and make it do the right thing. Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Acked-by:

Paolo Bonzini <pbonzini@redhat.com> Acked-by:

Andy Lutomirski <luto@kernel.org>

arch/x86/kvm/vmx/vmx.c

+0 −8

Original line number	Diff line number	Diff line
		@@ -1338,14 +1338,6 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu)
		(unsigned long)&get_cpu_entry_area(cpu)->tss.x86_tss);
		vmcs_writel(HOST_GDTR_BASE, (unsigned long)gdt); /* 22.2.4 */

		/*
		* VM exits change the host TR limit to 0x67 after a VM
		* exit. This is okay, since 0x67 covers everything except
		* the IO bitmap and have have code to handle the IO bitmap
		* being lost after a VM exit.
		*/
		BUILD_BUG_ON(IO_BITMAP_OFFSET - 1 != 0x67);

		rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
		vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */

arch/x86/mm/cpu_entry_area.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -161,6 +161,14 @@ static void __init setup_cpu_entry_area(unsigned int cpu)
		BUILD_BUG_ON((offsetof(struct tss_struct, x86_tss) ^
		offsetofend(struct tss_struct, x86_tss)) & PAGE_MASK);
		BUILD_BUG_ON(sizeof(struct tss_struct) % PAGE_SIZE != 0);
		/*
		* VMX changes the host TR limit to 0x67 after a VM exit. This is
		* okay, since 0x67 covers the size of struct x86_hw_tss. Make sure
		* that this is correct.
		*/
		BUILD_BUG_ON(offsetof(struct tss_struct, x86_tss) != 0);
		BUILD_BUG_ON(sizeof(struct x86_hw_tss) != 0x68);

		cea_map_percpu_pages(&cea->tss, &per_cpu(cpu_tss_rw, cpu),
		sizeof(struct tss_struct) / PAGE_SIZE, tss_prot);

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