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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	"David P . Reed" <dpreed@deepplum.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Uros Bizjak <ubizjak@gmail.com>
Subject: [PATCH 4/9] KVM/nVMX: Use __vmx_vcpu_run in nested_vmx_check_vmentry_hw
Date: Wed, 30 Dec 2020 16:26:57 -0800	[thread overview]
Message-ID: <20201231002702.2223707-5-seanjc@google.com> (raw)
In-Reply-To: <20201231002702.2223707-1-seanjc@google.com>

From: Uros Bizjak <ubizjak@gmail.com>

Replace inline assembly in nested_vmx_check_vmentry_hw
with a call to __vmx_vcpu_run.  The function is not
performance critical, so (double) GPR save/restore
in __vmx_vcpu_run can be tolerated, as far as performance
effects are concerned.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Reviewed-and-tested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
[sean: dropped versioning info from changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/vmx/nested.c  | 32 +++-----------------------------
 arch/x86/kvm/vmx/vmenter.S |  2 +-
 arch/x86/kvm/vmx/vmx.c     |  2 --
 arch/x86/kvm/vmx/vmx.h     |  1 +
 4 files changed, 5 insertions(+), 32 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index e2f26564a12d..5bbb4d667370 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -12,6 +12,7 @@
 #include "nested.h"
 #include "pmu.h"
 #include "trace.h"
+#include "vmx.h"
 #include "x86.h"
 
 static bool __read_mostly enable_shadow_vmcs = 1;
@@ -3057,35 +3058,8 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
 		vmx->loaded_vmcs->host_state.cr4 = cr4;
 	}
 
-	asm(
-		"sub $%c[wordsize], %%" _ASM_SP "\n\t" /* temporarily adjust RSP for CALL */
-		"cmp %%" _ASM_SP ", %c[host_state_rsp](%[loaded_vmcs]) \n\t"
-		"je 1f \n\t"
-		__ex("vmwrite %%" _ASM_SP ", %[HOST_RSP]") "\n\t"
-		"mov %%" _ASM_SP ", %c[host_state_rsp](%[loaded_vmcs]) \n\t"
-		"1: \n\t"
-		"add $%c[wordsize], %%" _ASM_SP "\n\t" /* un-adjust RSP */
-
-		/* Check if vmlaunch or vmresume is needed */
-		"cmpb $0, %c[launched](%[loaded_vmcs])\n\t"
-
-		/*
-		 * VMLAUNCH and VMRESUME clear RFLAGS.{CF,ZF} on VM-Exit, set
-		 * RFLAGS.CF on VM-Fail Invalid and set RFLAGS.ZF on VM-Fail
-		 * Valid.  vmx_vmenter() directly "returns" RFLAGS, and so the
-		 * results of VM-Enter is captured via CC_{SET,OUT} to vm_fail.
-		 */
-		"call vmx_vmenter\n\t"
-
-		CC_SET(be)
-	      : ASM_CALL_CONSTRAINT, CC_OUT(be) (vm_fail)
-	      :	[HOST_RSP]"r"((unsigned long)HOST_RSP),
-		[loaded_vmcs]"r"(vmx->loaded_vmcs),
-		[launched]"i"(offsetof(struct loaded_vmcs, launched)),
-		[host_state_rsp]"i"(offsetof(struct loaded_vmcs, host_state.rsp)),
-		[wordsize]"i"(sizeof(ulong))
-	      : "memory"
-	);
+	vm_fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs,
+				 vmx->loaded_vmcs->launched);
 
 	if (vmx->msr_autoload.host.nr)
 		vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr);
diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
index e85aa5faa22d..3a6461694fc2 100644
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -44,7 +44,7 @@
  * they VM-Fail, whereas a successful VM-Enter + VM-Exit will jump
  * to vmx_vmexit.
  */
-SYM_FUNC_START(vmx_vmenter)
+SYM_FUNC_START_LOCAL(vmx_vmenter)
 	/* EFLAGS.ZF is set if VMCS.LAUNCHED == 0 */
 	je 2f
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 75c9c6a0a3a4..65b5f02b199f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6577,8 +6577,6 @@ static fastpath_t vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
 	}
 }
 
-bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
-
 static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
 					struct vcpu_vmx *vmx)
 {
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 9d3a557949ac..03fc90569ae1 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -339,6 +339,7 @@ void vmx_set_virtual_apic_mode(struct kvm_vcpu *vcpu);
 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);
 int vmx_find_loadstore_msr_slot(struct vmx_msrs *m, u32 msr);
 void vmx_ept_load_pdptrs(struct kvm_vcpu *vcpu);
 
-- 
2.29.2.729.g45daf8777d-goog


  parent reply	other threads:[~2020-12-31  0:29 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-31  0:26 [PATCH 0/9] x86/virt: KVM: x86: Exception handling fixes/cleanups Sean Christopherson
2020-12-31  0:26 ` [PATCH 1/9] x86/virt: Eat faults on VMXOFF in reboot flows Sean Christopherson
2020-12-31  0:26 ` [PATCH 2/9] x86/reboot: Force all cpus to exit VMX root if VMX is supported Sean Christopherson
2020-12-31  0:26 ` [PATCH 3/9] x86/virt: Mark flags and memory as clobbered by VMXOFF Sean Christopherson
2020-12-31  0:26 ` Sean Christopherson [this message]
2020-12-31  0:26 ` [PATCH 5/9] KVM: VMX: Move Intel PT shenanigans out of VMXON/VMXOFF flows Sean Christopherson
2020-12-31  0:26 ` [PATCH 6/9] KVM: VMX: Use the kernel's version of VMXOFF Sean Christopherson
2020-12-31  0:27 ` [PATCH 7/9] KVM: SVM: Use asm goto to handle unexpected #UD on SVM instructions Sean Christopherson
2020-12-31  0:27 ` [PATCH 8/9] KVM: x86: Kill off __ex() and __kvm_handle_fault_on_reboot() Sean Christopherson
2020-12-31  0:27 ` [PATCH 9/9] KVM: x86: Move declaration of kvm_spurious_fault() to x86.h Sean Christopherson
2021-01-27 17:26 ` [PATCH 0/9] x86/virt: KVM: x86: Exception handling fixes/cleanups Paolo Bonzini

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