From 35a7831912f455d7d19b31cd9300e73f585a077b Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 30 Dec 2020 16:27:00 -0800 Subject: [PATCH] KVM: SVM: Use asm goto to handle unexpected #UD on SVM instructions Add svm_asm*() macros, a la the existing vmx_asm*() macros, to handle faults on SVM instructions instead of using the generic __ex(), a.k.a. __kvm_handle_fault_on_reboot(). Using asm goto generates slightly better code as it eliminates the in-line JMP+CALL sequences that are needed by __kvm_handle_fault_on_reboot() to avoid triggering BUG() from fixup (which generates bad stack traces). Using SVM specific macros also drops the last user of __ex() and the the last asm linkage to kvm_spurious_fault(), and adds a helper for VMSAVE, which may gain an addition call site in the future (as part of optimizing the SVM context switching). Signed-off-by: Sean Christopherson Message-Id: <20201231002702.2223707-8-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 3 ++- arch/x86/kvm/svm/svm.c | 16 +----------- arch/x86/kvm/svm/svm_ops.h | 64 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 67 insertions(+), 16 deletions(-) create mode 100644 arch/x86/kvm/svm/svm_ops.h diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 8dfe8988be8d..a3e2b29f484d 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -22,6 +22,7 @@ #include "x86.h" #include "svm.h" +#include "svm_ops.h" #include "cpuid.h" #include "trace.h" @@ -2076,7 +2077,7 @@ void sev_es_vcpu_load(struct vcpu_svm *svm, int cpu) * of which one step is to perform a VMLOAD. Since hardware does not * perform a VMSAVE on VMRUN, the host savearea must be updated. */ - asm volatile(__ex("vmsave %0") : : "a" (__sme_page_pa(sd->save_area)) : "memory"); + vmsave(__sme_page_pa(sd->save_area)); /* * Certain MSRs are restored on VMEXIT, only save ones that aren't diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 504e9474547b..58f771b48c2e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -41,6 +41,7 @@ #include "trace.h" #include "svm.h" +#include "svm_ops.h" #define __ex(x) __kvm_handle_fault_on_reboot(x) @@ -248,21 +249,6 @@ u32 svm_msrpm_offset(u32 msr) #define MAX_INST_SIZE 15 -static inline void clgi(void) -{ - asm volatile (__ex("clgi")); -} - -static inline void stgi(void) -{ - asm volatile (__ex("stgi")); -} - -static inline void invlpga(unsigned long addr, u32 asid) -{ - asm volatile (__ex("invlpga %1, %0") : : "c"(asid), "a"(addr)); -} - static int get_max_npt_level(void) { #ifdef CONFIG_X86_64 diff --git a/arch/x86/kvm/svm/svm_ops.h b/arch/x86/kvm/svm/svm_ops.h new file mode 100644 index 000000000000..9f007bc8409a --- /dev/null +++ b/arch/x86/kvm/svm/svm_ops.h @@ -0,0 +1,64 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __KVM_X86_SVM_OPS_H +#define __KVM_X86_SVM_OPS_H + +#include + +#include + +#define svm_asm(insn, clobber...) \ +do { \ + asm_volatile_goto("1: " __stringify(insn) "\n\t" \ + _ASM_EXTABLE(1b, %l[fault]) \ + ::: clobber : fault); \ + return; \ +fault: \ + kvm_spurious_fault(); \ +} while (0) + +#define svm_asm1(insn, op1, clobber...) \ +do { \ + asm_volatile_goto("1: " __stringify(insn) " %0\n\t" \ + _ASM_EXTABLE(1b, %l[fault]) \ + :: op1 : clobber : fault); \ + return; \ +fault: \ + kvm_spurious_fault(); \ +} while (0) + +#define svm_asm2(insn, op1, op2, clobber...) \ +do { \ + asm_volatile_goto("1: " __stringify(insn) " %1, %0\n\t" \ + _ASM_EXTABLE(1b, %l[fault]) \ + :: op1, op2 : clobber : fault); \ + return; \ +fault: \ + kvm_spurious_fault(); \ +} while (0) + +static inline void clgi(void) +{ + svm_asm(clgi); +} + +static inline void stgi(void) +{ + svm_asm(stgi); +} + +static inline void invlpga(unsigned long addr, u32 asid) +{ + svm_asm2(invlpga, "c"(asid), "a"(addr)); +} + +/* + * Despite being a physical address, the portion of rAX that is consumed by + * VMSAVE, VMLOAD, etc... is still controlled by the effective address size, + * hence 'unsigned long' instead of 'hpa_t'. + */ +static inline void vmsave(unsigned long pa) +{ + svm_asm1(vmsave, "a" (pa), "memory"); +} + +#endif /* __KVM_X86_SVM_OPS_H */ -- 2.11.0