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KVM: VMX: Convert launched argument to flags

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commit bb06650634d3552c0f8557e9d16aa1a408040e28 upstream.

Convert __vmx_vcpu_run()'s 'launched' argument to 'flags', in
preparation for doing SPEC_CTRL handling immediately after vmexit, which
will need another flag.

This is much easier than adding a fourth argument, because this code
supports both 32-bit and 64-bit, and the fourth argument on 32-bit would
have to be pushed on the stack.

Note that __vmx_vcpu_run_flags() is called outside of the noinstr
critical section because it will soon start calling potentially
traceable functions.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thadeu Lima de Souza Cascardo 2022-10-03 10:10:28 -03:00 committed by Greg Kroah-Hartman
parent 5895a9297e
commit a31bdec99a
5 changed files with 28 additions and 7 deletions
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2
arch/x86/kvm/vmx/nested.c
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@ -2865,7 +2865,7 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
}
vm_fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs,
vmx->loaded_vmcs->launched);
__vmx_vcpu_run_flags(vmx));
if (vmx->msr_autoload.host.nr)
vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr);

7
arch/x86/kvm/vmx/run_flags.h Normal file
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@ -0,0 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __KVM_X86_VMX_RUN_FLAGS_H
#define __KVM_X86_VMX_RUN_FLAGS_H
#define VMX_RUN_VMRESUME (1 << 0)
#endif /* __KVM_X86_VMX_RUN_FLAGS_H */

9
arch/x86/kvm/vmx/vmenter.S
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@ -4,6 +4,7 @@
#include <asm/bitsperlong.h>
#include <asm/kvm_vcpu_regs.h>
#include <asm/nospec-branch.h>
#include "run_flags.h"
#define WORD_SIZE (BITS_PER_LONG / 8)
@ -33,7 +34,7 @@
* __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode
* @vmx: struct vcpu_vmx * (forwarded to vmx_update_host_rsp)
* @regs: unsigned long * (to guest registers)
* @launched: %true if the VMCS has been launched
* @flags: VMX_RUN_VMRESUME: use VMRESUME instead of VMLAUNCH
*
* Returns:
* 0 on VM-Exit, 1 on VM-Fail
@ -58,7 +59,7 @@ ENTRY(__vmx_vcpu_run)
*/
push %_ASM_ARG2
/* Copy @launched to BL, _ASM_ARG3 is volatile. */
/* Copy @flags to BL, _ASM_ARG3 is volatile. */
mov %_ASM_ARG3B, %bl
lea (%_ASM_SP), %_ASM_ARG2
@ -68,7 +69,7 @@ ENTRY(__vmx_vcpu_run)
mov (%_ASM_SP), %_ASM_AX
/* Check if vmlaunch or vmresume is needed */
testb %bl, %bl
testb $VMX_RUN_VMRESUME, %bl
/* Load guest registers. Don't clobber flags. */
mov VCPU_RBX(%_ASM_AX), %_ASM_BX
@ -91,7 +92,7 @@ ENTRY(__vmx_vcpu_run)
mov VCPU_RAX(%_ASM_AX), %_ASM_AX
/* Check EFLAGS.ZF from 'testb' above */
je .Lvmlaunch
jz .Lvmlaunch
/*
* If VMRESUME/VMLAUNCH and corresponding vmexit succeed, execution resumes at

12
arch/x86/kvm/vmx/vmx.c
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@ -863,6 +863,16 @@ static bool msr_write_intercepted(struct vcpu_vmx *vmx, u32 msr)
return true;
}
unsigned int __vmx_vcpu_run_flags(struct vcpu_vmx *vmx)
{
unsigned int flags = 0;
if (vmx->loaded_vmcs->launched)
flags |= VMX_RUN_VMRESUME;
return flags;
}
static void clear_atomic_switch_msr_special(struct vcpu_vmx *vmx,
unsigned long entry, unsigned long exit)
{
@ -6627,7 +6637,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
write_cr2(vcpu->arch.cr2);
vmx->fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs,
vmx->loaded_vmcs->launched);
__vmx_vcpu_run_flags(vmx));
vcpu->arch.cr2 = read_cr2();

5
arch/x86/kvm/vmx/vmx.h
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@ -10,6 +10,7 @@
#include "capabilities.h"
#include "ops.h"
#include "vmcs.h"
#include "run_flags.h"
extern const u32 vmx_msr_index[];
extern u64 host_efer;
@ -336,7 +337,9 @@ void vmx_set_virtual_apic_mode(struct kvm_vcpu *vcpu);
struct shared_msr_entry *find_msr_entry(struct vcpu_vmx *vmx, u32 msr);
void pt_update_intercept_for_msr(struct vcpu_vmx *vmx);
void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp);
bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
unsigned int __vmx_vcpu_run_flags(struct vcpu_vmx *vmx);
bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs,
unsigned int flags);
#define POSTED_INTR_ON 0
#define POSTED_INTR_SN 1