[PATCH 5.18 48/61] KVM: VMX: Convert launched argument to flags

Greg Kroah-Hartman
2022-07-12T19:13:05Z

From: Josh Poimboeuf <jpoimboe@kernel.org>

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>
---
arch/x86/kvm/vmx/nested.c | 2 +-
arch/x86/kvm/vmx/run_flags.h | 7 +++++++
arch/x86/kvm/vmx/vmenter.S | 9 +++++----
arch/x86/kvm/vmx/vmx.c | 17 ++++++++++++++---
arch/x86/kvm/vmx/vmx.h | 5 ++++-
5 files changed, 31 insertions(+), 9 deletions(-)
create mode 100644 arch/x86/kvm/vmx/run_flags.h

--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3091,7 +3091,7 @@ static int nested_vmx_check_vmentry_hw(s
}

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);
--- /dev/null
+++ b/arch/x86/kvm/vmx/run_flags.h
@@ -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 */
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -5,6 +5,7 @@
#include <asm/kvm_vcpu_regs.h>
#include <asm/nospec-branch.h>
#include <asm/segment.h>
+#include "run_flags.h"

#define WORD_SIZE (BITS_PER_LONG / 8)

@@ -34,7 +35,7 @@
* __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
@@ -59,7 +60,7 @@ SYM_FUNC_START(__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
@@ -69,7 +70,7 @@ SYM_FUNC_START(__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_RCX(%_ASM_AX), %_ASM_CX
@@ -92,7 +93,7 @@ SYM_FUNC_START(__vmx_vcpu_run)
mov VCPU_RAX(%_ASM_AX), %_ASM_AX

/* Check EFLAGS.ZF from 'testb' above */
- je .Lvmlaunch
+ jz .Lvmlaunch

/*
* After a successful VMRESUME/VMLAUNCH, control flow "magically"
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -839,6 +839,16 @@ static bool msr_write_intercepted(struct
MSR_IA32_SPEC_CTRL);
}

+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)
{
@@ -6827,7 +6837,8 @@ static fastpath_t vmx_exit_handlers_fast
}

static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
- struct vcpu_vmx *vmx)
+ struct vcpu_vmx *vmx,
+ unsigned long flags)
{
guest_state_enter_irqoff();

@@ -6846,7 +6857,7 @@ static noinstr void vmx_vcpu_enter_exit(
native_write_cr2(vcpu->arch.cr2);

vmx->fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs,
- vmx->loaded_vmcs->launched);
+ flags);

vcpu->arch.cr2 = native_read_cr2();

@@ -6954,7 +6965,7 @@ static fastpath_t vmx_vcpu_run(struct kv
x86_spec_ctrl_set_guest(vmx->spec_ctrl, 0);

/* The actual VMENTER/EXIT is in the .noinstr.text section. */
- vmx_vcpu_enter_exit(vcpu, vmx);
+ vmx_vcpu_enter_exit(vcpu, vmx, __vmx_vcpu_run_flags(vmx));

/*
* We do not use IBRS in the kernel. If this vCPU has used the
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -13,6 +13,7 @@
#include "vmcs.h"
#include "vmx_ops.h"
#include "cpuid.h"
+#include "run_flags.h"

#define MSR_TYPE_R 1
#define MSR_TYPE_W 2
@@ -404,7 +405,9 @@ void vmx_set_virtual_apic_mode(struct kv
struct vmx_uret_msr *vmx_find_uret_msr(struct vcpu_vmx *vmx, u32 msr);
void pt_update_intercept_for_msr(struct kvm_vcpu *vcpu);
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);
int vmx_find_loadstore_msr_slot(struct vmx_msrs *m, u32 msr);
void vmx_ept_load_pdptrs(struct kvm_vcpu *vcpu);