On 08.11.23 12:17, Nicolas Saenz Julienne wrote:
VTL call/return hypercalls have their own entry points in the hypercall
page because they don't follow normal hyper-v hypercall conventions.
Move the VTL call/return control input into ECX/RAX and set the
hypercall code into EAX/RCX before calling the hypercall instruction in
order to be able to use the Hyper-V hypercall entry function.
Guests can read an emulated code page offsets register to know the
offsets into the hypercall page for the VTL call/return entries.
Signed-off-by: Nicolas Saenz Julienne <nsa...@amazon.com>
---
My tree has the additional patch, we're still trying to understand under
what conditions Windows expects the offset to be fixed.
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 54f7f36a89bf..9f2ea8c34447 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -294,6 +294,7 @@ static int patch_hypercall_page(struct kvm_vcpu *vcpu, u64
data)
/* VTL call/return entries */
if (!kvm_xen_hypercall_enabled(kvm) && kvm_hv_vsm_enabled(kvm)) {
+ i = 22;
#ifdef CONFIG_X86_64
if (is_64_bit_mode(vcpu)) {
/*
---
arch/x86/include/asm/kvm_host.h | 2 +
arch/x86/kvm/hyperv.c | 78 ++++++++++++++++++++++++++++++-
include/asm-generic/hyperv-tlfs.h | 11 +++++
3 files changed, 90 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a2f224f95404..00cd21b09f8c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1105,6 +1105,8 @@ struct kvm_hv {
u64 hv_tsc_emulation_status;
u64 hv_invtsc_control;
+ union hv_register_vsm_code_page_offsets vsm_code_page_offsets;
+
/* How many vCPUs have VP index != vCPU index */
atomic_t num_mismatched_vp_indexes;
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 78d053042667..d4b1b53ea63d 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -259,7 +259,8 @@ static void synic_exit(struct kvm_vcpu_hv_synic *synic, u32
msr)
static int patch_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
{
struct kvm *kvm = vcpu->kvm;
- u8 instructions[9];
+ struct kvm_hv *hv = to_kvm_hv(kvm);
+ u8 instructions[0x30];
int i = 0;
u64 addr;
@@ -285,6 +286,81 @@ static int patch_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
/* ret */
((unsigned char *)instructions)[i++] = 0xc3;
+ /* VTL call/return entries */
+ if (!kvm_xen_hypercall_enabled(kvm) && kvm_hv_vsm_enabled(kvm)) {
You don't introduce kvm_hv_vsm_enabled() before. Please do a quick test
build of all individual commits of your patch set for v1 :).
+#ifdef CONFIG_X86_64
Why do you need the ifdef here? is_long_mode() already has an ifdef that
will always return false for is_64_bit_mode() on 32bit hosts.
+ if (is_64_bit_mode(vcpu)) {
+ /*
+ * VTL call 64-bit entry prologue:
+ * mov %rcx, %rax
+ * mov $0x11, %ecx
+ * jmp 0:
+ */
+ hv->vsm_code_page_offsets.vtl_call_offset = i;
+ instructions[i++] = 0x48;
+ instructions[i++] = 0x89;
+ instructions[i++] = 0xc8;
+ instructions[i++] = 0xb9;
+ instructions[i++] = 0x11;
+ instructions[i++] = 0x00;
+ instructions[i++] = 0x00;
+ instructions[i++] = 0x00;
+ instructions[i++] = 0xeb;
+ instructions[i++] = 0xe0;
I think it would be a lot easier to read (because it's denser) if you
move the opcodes into a character array:
char vtl_entry[] = { 0x48, 0x89, 0xc8, 0xb9, 0x11, 0x00, 0x00, 0x00.
0xeb, 0xe0 };
and then just memcpy().
Alex
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
