168 lines
6.0 KiB
Diff
168 lines
6.0 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Maxim Levitsky <mlevitsk@redhat.com>
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Date: Tue, 21 Jun 2022 18:09:02 +0300
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Subject: [PATCH] KVM: x86: emulator/smm: preserve interrupt shadow in SMRAM
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When #SMI is asserted, the CPU can be in interrupt shadow
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due to sti or mov ss.
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It is not mandatory in Intel/AMD prm to have the #SMI
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blocked during the shadow, and on top of
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that, since neither SVM nor VMX has true support for SMI
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window, waiting for one instruction would mean single stepping
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the guest.
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Instead, allow #SMI in this case, but both reset the interrupt
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window and stash its value in SMRAM to restore it on exit
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from SMM.
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This fixes rare failures seen mostly on windows guests on VMX,
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when #SMI falls on the sti instruction which mainfest in
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VM entry failure due to EFLAGS.IF not being set, but STI interrupt
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window still being set in the VMCS.
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Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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arch/x86/kvm/emulate.c | 17 ++++++++++++++---
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arch/x86/kvm/kvm_emulate.h | 13 ++++++++++---
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arch/x86/kvm/x86.c | 12 ++++++++++++
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3 files changed, 36 insertions(+), 6 deletions(-)
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diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
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index 98c2cf169b39..5614456de922 100644
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--- a/arch/x86/kvm/emulate.c
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+++ b/arch/x86/kvm/emulate.c
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@@ -2416,7 +2416,7 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,
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struct kvm_smram_state_32 *smstate)
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{
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struct desc_ptr dt;
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- int i;
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+ int i, r;
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ctxt->eflags = smstate->eflags | X86_EFLAGS_FIXED;
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ctxt->_eip = smstate->eip;
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@@ -2451,8 +2451,16 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,
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ctxt->ops->set_smbase(ctxt, smstate->smbase);
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- return rsm_enter_protected_mode(ctxt, smstate->cr0,
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- smstate->cr3, smstate->cr4);
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+ r = rsm_enter_protected_mode(ctxt, smstate->cr0,
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+ smstate->cr3, smstate->cr4);
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+
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+ if (r != X86EMUL_CONTINUE)
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+ return r;
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+
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+ ctxt->ops->set_int_shadow(ctxt, 0);
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+ ctxt->interruptibility = (u8)smstate->int_shadow;
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+
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+ return X86EMUL_CONTINUE;
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}
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#ifdef CONFIG_X86_64
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@@ -2501,6 +2509,9 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,
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rsm_load_seg_64(ctxt, &smstate->fs, VCPU_SREG_FS);
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rsm_load_seg_64(ctxt, &smstate->gs, VCPU_SREG_GS);
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+ ctxt->ops->set_int_shadow(ctxt, 0);
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+ ctxt->interruptibility = (u8)smstate->int_shadow;
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+
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return X86EMUL_CONTINUE;
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}
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#endif
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diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
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index d16b377be70b..5b881a3a5ed9 100644
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--- a/arch/x86/kvm/kvm_emulate.h
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+++ b/arch/x86/kvm/kvm_emulate.h
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@@ -229,6 +229,7 @@ struct x86_emulate_ops {
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bool (*guest_has_rdpid)(struct x86_emulate_ctxt *ctxt);
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void (*set_nmi_mask)(struct x86_emulate_ctxt *ctxt, bool masked);
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+ void (*set_int_shadow)(struct x86_emulate_ctxt *ctxt, u8 shadow);
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unsigned (*get_hflags)(struct x86_emulate_ctxt *ctxt);
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void (*exiting_smm)(struct x86_emulate_ctxt *ctxt);
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@@ -499,7 +500,9 @@ struct kvm_smram_state_32 {
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u32 reserved1[62]; /* FE00 - FEF7 */
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u32 smbase; /* FEF8 */
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u32 smm_revision; /* FEFC */
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- u32 reserved2[5]; /* FF00-FF13 */
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+ u32 reserved2[4]; /* FF00-FF0F*/
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+ /* int_shadow is KVM extension*/
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+ u32 int_shadow; /* FF10 */
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/* CR4 is not present in Intel/AMD SMRAM image*/
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u32 cr4; /* FF14 */
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u32 reserved3[5]; /* FF18 */
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@@ -571,13 +574,17 @@ struct kvm_smram_state_64 {
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struct kvm_smm_seg_state_64 idtr; /* FE80 (R/O) */
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struct kvm_smm_seg_state_64 tr; /* FE90 (R/O) */
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- /* I/O restart and auto halt restart are not implemented by KVM */
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+ /*
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+ * I/O restart and auto halt restart are not implemented by KVM
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+ * int_shadow is KVM's extension
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+ */
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+
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u64 io_restart_rip; /* FEA0 (R/O) */
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u64 io_restart_rcx; /* FEA8 (R/O) */
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u64 io_restart_rsi; /* FEB0 (R/O) */
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u64 io_restart_rdi; /* FEB8 (R/O) */
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u32 io_restart_dword; /* FEC0 (R/O) */
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- u32 reserved1; /* FEC4 */
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+ u32 int_shadow; /* FEC4 (R/O) */
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u8 io_instruction_restart; /* FEC8 (R/W) */
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u8 auto_halt_restart; /* FEC9 (R/W) */
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u8 reserved2[6]; /* FECA-FECF */
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diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
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index f40cd45b6a01..9afac97ea98c 100644
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--- a/arch/x86/kvm/x86.c
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+++ b/arch/x86/kvm/x86.c
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@@ -7299,6 +7299,11 @@ static void emulator_set_nmi_mask(struct x86_emulate_ctxt *ctxt, bool masked)
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static_call(kvm_x86_set_nmi_mask)(emul_to_vcpu(ctxt), masked);
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}
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+static void emulator_set_int_shadow(struct x86_emulate_ctxt *ctxt, u8 shadow)
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+{
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+ static_call(kvm_x86_set_interrupt_shadow)(emul_to_vcpu(ctxt), shadow);
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+}
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+
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static unsigned emulator_get_hflags(struct x86_emulate_ctxt *ctxt)
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{
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return emul_to_vcpu(ctxt)->arch.hflags;
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@@ -7368,6 +7373,7 @@ static const struct x86_emulate_ops emulate_ops = {
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.guest_has_fxsr = emulator_guest_has_fxsr,
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.guest_has_rdpid = emulator_guest_has_rdpid,
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.set_nmi_mask = emulator_set_nmi_mask,
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+ .set_int_shadow = emulator_set_int_shadow,
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.get_hflags = emulator_get_hflags,
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.exiting_smm = emulator_exiting_smm,
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.leave_smm = emulator_leave_smm,
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@@ -9088,6 +9094,8 @@ static void enter_smm_save_state_32(struct kvm_vcpu *vcpu, struct kvm_smram_stat
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smram->cr4 = kvm_read_cr4(vcpu);
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smram->smm_revision = 0x00020000;
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smram->smbase = vcpu->arch.smbase;
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+
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+ smram->int_shadow = static_call(kvm_x86_get_interrupt_shadow)(vcpu);
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}
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#ifdef CONFIG_X86_64
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@@ -9136,6 +9144,8 @@ static void enter_smm_save_state_64(struct kvm_vcpu *vcpu, struct kvm_smram_stat
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enter_smm_save_seg_64(vcpu, &smram->ds, VCPU_SREG_DS);
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enter_smm_save_seg_64(vcpu, &smram->fs, VCPU_SREG_FS);
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enter_smm_save_seg_64(vcpu, &smram->gs, VCPU_SREG_GS);
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+
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+ smram->int_shadow = static_call(kvm_x86_get_interrupt_shadow)(vcpu);
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}
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#endif
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@@ -9172,6 +9182,8 @@ static void enter_smm(struct kvm_vcpu *vcpu)
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kvm_set_rflags(vcpu, X86_EFLAGS_FIXED);
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kvm_rip_write(vcpu, 0x8000);
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+ static_call(kvm_x86_set_interrupt_shadow)(vcpu, 0);
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+
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cr0 = vcpu->arch.cr0 & ~(X86_CR0_PE | X86_CR0_EM | X86_CR0_TS | X86_CR0_PG);
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static_call(kvm_x86_set_cr0)(vcpu, cr0);
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vcpu->arch.cr0 = cr0;
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