Re: [kvm-devel] [PATCH] Refactor hypercall infrastructure (v2)
Amit Shah wrote: * Anthony Liguori wrote: Amit Shah wrote: * Anthony Liguori wrote: This patch refactors the current hypercall infrastructure to better support live migration and SMP. It eliminates the hypercall page by trapping the UD exception that would occur if you used the wrong hypercall instruction for the underlying architecture and replacing it with the right one lazily. This doesn't work right for SVM. It keeps looping indefinitely; on a kvm_stat run, I get about 230,000 light vm exits per second, with the hypercall never returning to the guest. ... What are you using to issue the hypercall? + r = kvm_hypercall1(KVM_PV_PCI_DEVICE, page_gfn); Setup is done by: + if (!kvm_para_available()) { + printk(KERN_ERR KVM paravirt support not available\n); + r = -ENODEV; + goto out_dereg; + } There was a bug where instructions with a modrm byte specifying a register would try to access memory. In the memory was not mapped, emulation would fail. vmcall is one such instruction. This was fixed by commit f83562246921d6a8a7de8b76853a6835ace3699d Author: Aurelien Jarno [EMAIL PROTECTED] Date: Wed Oct 17 19:30:41 2007 +0200 KVM: x86 emulator: fix access registers for instructions with ModR/M byte and Mod = 3 The patch belows changes the access type to register from memory for instructions that are declared as SrcMem or DstMem, but have a ModR/M byte with Mod = 3. It fixes (at least) the lmsw and smsw instructions on an AMD64 CPU, which are needed for FreeBSD. Signed-off-by: Aurelien Jarno [EMAIL PROTECTED] Signed-off-by: Avi Kivity [EMAIL PROTECTED] diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c index 7c95ae5..8c50496 100644 --- a/drivers/kvm/x86_emulate.c +++ b/drivers/kvm/x86_emulate.c @@ -835,6 +835,14 @@ modrm_done: if (c-twobyte c-b == 0x01 c-modrm_reg == 7) break; + /* +* For instructions with a ModR/M byte, switch to register +* access if Mod = 3. +*/ + if ((c-d ModRM) c-modrm_mod == 3) { + c-src.type = OP_REG; + break; + } srcmem_common: c-src.type = OP_MEM; break; @@ -897,7 +905,14 @@ srcmem_common: } break; case DstMem: - c-dst.type = OP_MEM; + /* +* For instructions with a ModR/M byte, switch to register +* access if Mod = 3. +*/ + if ((c-d ModRM) c-modrm_mod == 3) + c-dst.type = OP_REG; + else + c-dst.type = OP_MEM; break; } -- error compiling committee.c: too many arguments to function - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] [PATCH] Refactor hypercall infrastructure (v2)
* Anthony Liguori wrote: Amit Shah wrote: * Anthony Liguori wrote: This patch refactors the current hypercall infrastructure to better support live migration and SMP. It eliminates the hypercall page by trapping the UD exception that would occur if you used the wrong hypercall instruction for the underlying architecture and replacing it with the right one lazily. This doesn't work right for SVM. It keeps looping indefinitely; on a kvm_stat run, I get about 230,000 light vm exits per second, with the hypercall never returning to the guest. ... What are you using to issue the hypercall? + r = kvm_hypercall1(KVM_PV_PCI_DEVICE, page_gfn); Setup is done by: + if (!kvm_para_available()) { + printk(KERN_ERR KVM paravirt support not available\n); + r = -ENODEV; + goto out_dereg; + } I also couldn't get the has_feature to work properly. See: http://lkml.org/lkml/2007/11/7/129 I had to change the hypercall address to 0f 01 d9 for it to get working. Regards, Anthony Liguori - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] [PATCH] Refactor hypercall infrastructure (v2)
* Avi Kivity wrote: Amit Shah wrote: * Anthony Liguori wrote: Amit Shah wrote: What are you using to issue the hypercall? + r = kvm_hypercall1(KVM_PV_PCI_DEVICE, page_gfn); Setup is done by: + if (!kvm_para_available()) { + printk(KERN_ERR KVM paravirt support not available\n); + r = -ENODEV; + goto out_dereg; + } There was a bug where instructions with a modrm byte specifying a register would try to access memory. In the memory was not mapped, emulation would fail. vmcall is one such instruction. This was fixed by commit f83562246921d6a8a7de8b76853a6835ace3699d Author: Aurelien Jarno [EMAIL PROTECTED] Date: Wed Oct 17 19:30:41 2007 +0200 KVM: x86 emulator: fix access registers for instructions with ModR/M byte and Mod = 3 Thanks, and thank you, Aurelien! - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] [PATCH] Refactor hypercall infrastructure (v2)
* Anthony Liguori wrote: This patch refactors the current hypercall infrastructure to better support live migration and SMP. It eliminates the hypercall page by trapping the UD exception that would occur if you used the wrong hypercall instruction for the underlying architecture and replacing it with the right one lazily. This doesn't work right for SVM. It keeps looping indefinitely; on a kvm_stat run, I get about 230,000 light vm exits per second, with the hypercall never returning to the guest. ... diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c index 729f1cd..d09a9f5 100644 --- a/drivers/kvm/svm.c +++ b/drivers/kvm/svm.c @@ -476,7 +476,8 @@ static void init_vmcb(struct vmcb *vmcb) INTERCEPT_DR5_MASK | INTERCEPT_DR7_MASK; - control-intercept_exceptions = 1 PF_VECTOR; + control-intercept_exceptions = (1 PF_VECTOR) | + (1 UD_VECTOR); control-intercept =(1ULL INTERCEPT_INTR) | @@ -970,6 +971,17 @@ static int pf_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) return 0; } +static int ud_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) +{ + int er; + + er = emulate_instruction(svm-vcpu, kvm_run, 0, 0); + if (er != EMULATE_DONE) + inject_ud(svm-vcpu); + + return 1; +} + static int nm_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) { svm-vmcb-control.intercept_exceptions = ~(1 NM_VECTOR); @@ -1036,7 +1048,8 @@ static int vmmcall_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) { svm-next_rip = svm-vmcb-save.rip + 3; skip_emulated_instruction(svm-vcpu); - return kvm_hypercall(svm-vcpu, kvm_run); + kvm_emulate_hypercall(svm-vcpu); + return 1; } static int invalid_op_interception(struct vcpu_svm *svm, @@ -1232,6 +1245,7 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm, [SVM_EXIT_WRITE_DR3]= emulate_on_interception, [SVM_EXIT_WRITE_DR5]= emulate_on_interception, [SVM_EXIT_WRITE_DR7]= emulate_on_interception, + [SVM_EXIT_EXCP_BASE + UD_VECTOR]= ud_interception, [SVM_EXIT_EXCP_BASE + PF_VECTOR]= pf_interception, [SVM_EXIT_EXCP_BASE + NM_VECTOR]= nm_interception, [SVM_EXIT_INTR] = nop_on_interception, @@ -1664,7 +1678,6 @@ svm_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall) hypercall[0] = 0x0f; hypercall[1] = 0x01; hypercall[2] = 0xd9; - hypercall[3] = 0xc3; } ... +/* This instruction is vmcall. On non-VT architectures, it will generate a + * trap that we will then rewrite to the appropriate instruction. */ -#define __NR_hypercalls 0 +#define KVM_HYPERCALL .byte 0x0f,0x01,0xc1 .. which never happens. - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] [PATCH] Refactor hypercall infrastructure (v2)
Amit Shah wrote: * Anthony Liguori wrote: This patch refactors the current hypercall infrastructure to better support live migration and SMP. It eliminates the hypercall page by trapping the UD exception that would occur if you used the wrong hypercall instruction for the underlying architecture and replacing it with the right one lazily. This doesn't work right for SVM. It keeps looping indefinitely; on a kvm_stat run, I get about 230,000 light vm exits per second, with the hypercall never returning to the guest. I just tested kvm.git with (the new) hypercall.flat testcase. Seems to work fine. -- error compiling committee.c: too many arguments to function - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] [PATCH] Refactor hypercall infrastructure (v2)
Amit Shah wrote: * Anthony Liguori wrote: This patch refactors the current hypercall infrastructure to better support live migration and SMP. It eliminates the hypercall page by trapping the UD exception that would occur if you used the wrong hypercall instruction for the underlying architecture and replacing it with the right one lazily. This doesn't work right for SVM. It keeps looping indefinitely; on a kvm_stat run, I get about 230,000 light vm exits per second, with the hypercall never returning to the guest. ... What are you using to issue the hypercall? Regards, Anthony Liguori diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c index 729f1cd..d09a9f5 100644 --- a/drivers/kvm/svm.c +++ b/drivers/kvm/svm.c @@ -476,7 +476,8 @@ static void init_vmcb(struct vmcb *vmcb) INTERCEPT_DR5_MASK | INTERCEPT_DR7_MASK; -control-intercept_exceptions = 1 PF_VECTOR; +control-intercept_exceptions = (1 PF_VECTOR) | +(1 UD_VECTOR); control-intercept =(1ULL INTERCEPT_INTR) | @@ -970,6 +971,17 @@ static int pf_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) return 0; } +static int ud_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) +{ +int er; + +er = emulate_instruction(svm-vcpu, kvm_run, 0, 0); +if (er != EMULATE_DONE) +inject_ud(svm-vcpu); + +return 1; +} + static int nm_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) { svm-vmcb-control.intercept_exceptions = ~(1 NM_VECTOR); @@ -1036,7 +1048,8 @@ static int vmmcall_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) { svm-next_rip = svm-vmcb-save.rip + 3; skip_emulated_instruction(svm-vcpu); -return kvm_hypercall(svm-vcpu, kvm_run); +kvm_emulate_hypercall(svm-vcpu); +return 1; } static int invalid_op_interception(struct vcpu_svm *svm, @@ -1232,6 +1245,7 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm, [SVM_EXIT_WRITE_DR3] = emulate_on_interception, [SVM_EXIT_WRITE_DR5]= emulate_on_interception, [SVM_EXIT_WRITE_DR7]= emulate_on_interception, +[SVM_EXIT_EXCP_BASE + UD_VECTOR]= ud_interception, [SVM_EXIT_EXCP_BASE + PF_VECTOR]= pf_interception, [SVM_EXIT_EXCP_BASE + NM_VECTOR]= nm_interception, [SVM_EXIT_INTR] = nop_on_interception, @@ -1664,7 +1678,6 @@ svm_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall) hypercall[0] = 0x0f; hypercall[1] = 0x01; hypercall[2] = 0xd9; -hypercall[3] = 0xc3; } ... +/* This instruction is vmcall. On non-VT architectures, it will generate a + * trap that we will then rewrite to the appropriate instruction. */ -#define __NR_hypercalls 0 +#define KVM_HYPERCALL .byte 0x0f,0x01,0xc1 .. which never happens. - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel