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-rw-r--r--arch/x86/kvm/svm/nested.c39
-rw-r--r--arch/x86/kvm/svm/sev.c2
-rw-r--r--arch/x86/kvm/svm/svm.c38
3 files changed, 56 insertions, 23 deletions
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 90a1ca939627..9a2a62e5afeb 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -19,6 +19,7 @@
#include <linux/kernel.h>
#include <asm/msr-index.h>
+#include <asm/debugreg.h>
#include "kvm_emulate.h"
#include "trace.h"
@@ -267,7 +268,7 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
svm->vmcb->save.rsp = nested_vmcb->save.rsp;
svm->vmcb->save.rip = nested_vmcb->save.rip;
svm->vmcb->save.dr7 = nested_vmcb->save.dr7;
- svm->vmcb->save.dr6 = nested_vmcb->save.dr6;
+ svm->vcpu.arch.dr6 = nested_vmcb->save.dr6;
svm->vmcb->save.cpl = nested_vmcb->save.cpl;
svm->nested.vmcb_msrpm = nested_vmcb->control.msrpm_base_pa & ~0x0fffULL;
@@ -482,7 +483,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
nested_vmcb->save.rsp = vmcb->save.rsp;
nested_vmcb->save.rax = vmcb->save.rax;
nested_vmcb->save.dr7 = vmcb->save.dr7;
- nested_vmcb->save.dr6 = vmcb->save.dr6;
+ nested_vmcb->save.dr6 = svm->vcpu.arch.dr6;
nested_vmcb->save.cpl = vmcb->save.cpl;
nested_vmcb->control.int_ctl = vmcb->control.int_ctl;
@@ -606,26 +607,45 @@ static int nested_svm_exit_handled_msr(struct vcpu_svm *svm)
/* DB exceptions for our internal use must not cause vmexit */
static int nested_svm_intercept_db(struct vcpu_svm *svm)
{
- unsigned long dr6;
+ unsigned long dr6 = svm->vmcb->save.dr6;
+
+ /* Always catch it and pass it to userspace if debugging. */
+ if (svm->vcpu.guest_debug &
+ (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
+ return NESTED_EXIT_HOST;
/* if we're not singlestepping, it's not ours */
if (!svm->nmi_singlestep)
- return NESTED_EXIT_DONE;
+ goto reflected_db;
/* if it's not a singlestep exception, it's not ours */
- if (kvm_get_dr(&svm->vcpu, 6, &dr6))
- return NESTED_EXIT_DONE;
if (!(dr6 & DR6_BS))
- return NESTED_EXIT_DONE;
+ goto reflected_db;
/* if the guest is singlestepping, it should get the vmexit */
if (svm->nmi_singlestep_guest_rflags & X86_EFLAGS_TF) {
disable_nmi_singlestep(svm);
- return NESTED_EXIT_DONE;
+ goto reflected_db;
}
/* it's ours, the nested hypervisor must not see this one */
return NESTED_EXIT_HOST;
+
+reflected_db:
+ /*
+ * Synchronize guest DR6 here just like in kvm_deliver_exception_payload;
+ * it will be moved into the nested VMCB by nested_svm_vmexit. Once
+ * exceptions will be moved to svm_check_nested_events, all this stuff
+ * will just go away and we could just return NESTED_EXIT_HOST
+ * unconditionally. db_interception will queue the exception, which
+ * will be processed by svm_check_nested_events if a nested vmexit is
+ * required, and we will just use kvm_deliver_exception_payload to copy
+ * the payload to DR6 before vmexit.
+ */
+ WARN_ON(svm->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT);
+ svm->vcpu.arch.dr6 &= ~(DR_TRAP_BITS | DR6_RTM);
+ svm->vcpu.arch.dr6 |= dr6 & ~DR6_FIXED_1;
+ return NESTED_EXIT_DONE;
}
static int nested_svm_intercept_ioio(struct vcpu_svm *svm)
@@ -682,6 +702,9 @@ static int nested_svm_intercept(struct vcpu_svm *svm)
if (svm->nested.intercept_exceptions & excp_bits) {
if (exit_code == SVM_EXIT_EXCP_BASE + DB_VECTOR)
vmexit = nested_svm_intercept_db(svm);
+ else if (exit_code == SVM_EXIT_EXCP_BASE + BP_VECTOR &&
+ svm->vcpu.guest_debug & KVM_GUESTDBG_USE_SW_BP)
+ vmexit = NESTED_EXIT_HOST;
else
vmexit = NESTED_EXIT_DONE;
}
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index cf912b4aaba8..89f7f3aebd31 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -345,7 +345,7 @@ static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr,
return NULL;
/* Pin the user virtual address. */
- npinned = get_user_pages_fast(uaddr, npages, FOLL_WRITE, pages);
+ npinned = get_user_pages_fast(uaddr, npages, write ? FOLL_WRITE : 0, pages);
if (npinned != npages) {
pr_err("SEV: Failure locking %lu pages.\n", npages);
goto err;
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 2f379bacbb26..a862c768fd54 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1672,17 +1672,14 @@ static void new_asid(struct vcpu_svm *svm, struct svm_cpu_data *sd)
mark_dirty(svm->vmcb, VMCB_ASID);
}
-static u64 svm_get_dr6(struct kvm_vcpu *vcpu)
+static void svm_set_dr6(struct vcpu_svm *svm, unsigned long value)
{
- return to_svm(vcpu)->vmcb->save.dr6;
-}
-
-static void svm_set_dr6(struct kvm_vcpu *vcpu, unsigned long value)
-{
- struct vcpu_svm *svm = to_svm(vcpu);
+ struct vmcb *vmcb = svm->vmcb;
- svm->vmcb->save.dr6 = value;
- mark_dirty(svm->vmcb, VMCB_DR);
+ if (unlikely(value != vmcb->save.dr6)) {
+ vmcb->save.dr6 = value;
+ mark_dirty(vmcb, VMCB_DR);
+ }
}
static void svm_sync_dirty_debug_regs(struct kvm_vcpu *vcpu)
@@ -1693,9 +1690,12 @@ static void svm_sync_dirty_debug_regs(struct kvm_vcpu *vcpu)
get_debugreg(vcpu->arch.db[1], 1);
get_debugreg(vcpu->arch.db[2], 2);
get_debugreg(vcpu->arch.db[3], 3);
- vcpu->arch.dr6 = svm_get_dr6(vcpu);
+ /*
+ * We cannot reset svm->vmcb->save.dr6 to DR6_FIXED_1|DR6_RTM here,
+ * because db_interception might need it. We can do it before vmentry.
+ */
+ vcpu->arch.dr6 = svm->vmcb->save.dr6;
vcpu->arch.dr7 = svm->vmcb->save.dr7;
-
vcpu->arch.switch_db_regs &= ~KVM_DEBUGREG_WONT_EXIT;
set_dr_intercepts(svm);
}
@@ -1739,7 +1739,8 @@ static int db_interception(struct vcpu_svm *svm)
if (!(svm->vcpu.guest_debug &
(KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP)) &&
!svm->nmi_singlestep) {
- kvm_queue_exception(&svm->vcpu, DB_VECTOR);
+ u32 payload = (svm->vmcb->save.dr6 ^ DR6_RTM) & ~DR6_FIXED_1;
+ kvm_queue_exception_p(&svm->vcpu, DB_VECTOR, payload);
return 1;
}
@@ -1752,6 +1753,8 @@ static int db_interception(struct vcpu_svm *svm)
if (svm->vcpu.guest_debug &
(KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP)) {
kvm_run->exit_reason = KVM_EXIT_DEBUG;
+ kvm_run->debug.arch.dr6 = svm->vmcb->save.dr6;
+ kvm_run->debug.arch.dr7 = svm->vmcb->save.dr7;
kvm_run->debug.arch.pc =
svm->vmcb->save.cs.base + svm->vmcb->save.rip;
kvm_run->debug.arch.exception = DB_VECTOR;
@@ -3315,6 +3318,15 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
svm->vmcb->save.cr2 = vcpu->arch.cr2;
+ /*
+ * Run with all-zero DR6 unless needed, so that we can get the exact cause
+ * of a #DB.
+ */
+ if (unlikely(svm->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT))
+ svm_set_dr6(svm, vcpu->arch.dr6);
+ else
+ svm_set_dr6(svm, DR6_FIXED_1 | DR6_RTM);
+
clgi();
kvm_load_guest_xsave_state(vcpu);
@@ -3929,8 +3941,6 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
.set_idt = svm_set_idt,
.get_gdt = svm_get_gdt,
.set_gdt = svm_set_gdt,
- .get_dr6 = svm_get_dr6,
- .set_dr6 = svm_set_dr6,
.set_dr7 = svm_set_dr7,
.sync_dirty_debug_regs = svm_sync_dirty_debug_regs,
.cache_reg = svm_cache_reg,
generated by cgit v1.2.3-70-g09d2 (git 2.48.1) at 2025-03-24 06:58:53 +0000