[PATCH 1/4] KVM: x86: Move FPU register accessors into fpu.h

[PATCH 1/4] KVM: x86: Move FPU register accessors into fpu.h

[Siddharth Chandrasekaran]

Hyper-v XMM fast hypercalls use XMM registers to pass input/output
parameters. To access these, hyperv.c can reuse some FPU register
accessors defined in emulator.c. Move them to a common location so both
can access them.

While at it, reorder the parameters of these accessor methods to make
them more readable.

Cc: Alexander Graf <graf@amazon.com>
Cc: Evgeny Iakovlev <eyakovl@amazon.de>
Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
---
 arch/x86/kvm/emulate.c | 138 ++++++----------------------------------
 arch/x86/kvm/fpu.h     | 140 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 158 insertions(+), 120 deletions(-)
 create mode 100644 arch/x86/kvm/fpu.h

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f7970ba6219f..296f8f3ce988 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -22,7 +22,6 @@
 #include "kvm_cache_regs.h"
 #include "kvm_emulate.h"
 #include <linux/stringify.h>
-#include <asm/fpu/api.h>
 #include <asm/debugreg.h>
 #include <asm/nospec-branch.h>
 
@@ -30,6 +29,7 @@
 #include "tss.h"
 #include "mmu.h"
 #include "pmu.h"
+#include "fpu.h"
 
 /*
  * Operand types
@@ -1081,116 +1081,14 @@ static void fetch_register_operand(struct operand *op)
 	}
 }
 
-static void emulator_get_fpu(void)
-{
-	fpregs_lock();
-
-	fpregs_assert_state_consistent();
-	if (test_thread_flag(TIF_NEED_FPU_LOAD))
-		switch_fpu_return();
-}
-
-static void emulator_put_fpu(void)
-{
-	fpregs_unlock();
-}
-
-static void read_sse_reg(sse128_t *data, int reg)
-{
-	emulator_get_fpu();
-	switch (reg) {
-	case 0: asm("movdqa %%xmm0, %0" : "=m"(*data)); break;
-	case 1: asm("movdqa %%xmm1, %0" : "=m"(*data)); break;
-	case 2: asm("movdqa %%xmm2, %0" : "=m"(*data)); break;
-	case 3: asm("movdqa %%xmm3, %0" : "=m"(*data)); break;
-	case 4: asm("movdqa %%xmm4, %0" : "=m"(*data)); break;
-	case 5: asm("movdqa %%xmm5, %0" : "=m"(*data)); break;
-	case 6: asm("movdqa %%xmm6, %0" : "=m"(*data)); break;
-	case 7: asm("movdqa %%xmm7, %0" : "=m"(*data)); break;
-#ifdef CONFIG_X86_64
-	case 8: asm("movdqa %%xmm8, %0" : "=m"(*data)); break;
-	case 9: asm("movdqa %%xmm9, %0" : "=m"(*data)); break;
-	case 10: asm("movdqa %%xmm10, %0" : "=m"(*data)); break;
-	case 11: asm("movdqa %%xmm11, %0" : "=m"(*data)); break;
-	case 12: asm("movdqa %%xmm12, %0" : "=m"(*data)); break;
-	case 13: asm("movdqa %%xmm13, %0" : "=m"(*data)); break;
-	case 14: asm("movdqa %%xmm14, %0" : "=m"(*data)); break;
-	case 15: asm("movdqa %%xmm15, %0" : "=m"(*data)); break;
-#endif
-	default: BUG();
-	}
-	emulator_put_fpu();
-}
-
-static void write_sse_reg(sse128_t *data, int reg)
-{
-	emulator_get_fpu();
-	switch (reg) {
-	case 0: asm("movdqa %0, %%xmm0" : : "m"(*data)); break;
-	case 1: asm("movdqa %0, %%xmm1" : : "m"(*data)); break;
-	case 2: asm("movdqa %0, %%xmm2" : : "m"(*data)); break;
-	case 3: asm("movdqa %0, %%xmm3" : : "m"(*data)); break;
-	case 4: asm("movdqa %0, %%xmm4" : : "m"(*data)); break;
-	case 5: asm("movdqa %0, %%xmm5" : : "m"(*data)); break;
-	case 6: asm("movdqa %0, %%xmm6" : : "m"(*data)); break;
-	case 7: asm("movdqa %0, %%xmm7" : : "m"(*data)); break;
-#ifdef CONFIG_X86_64
-	case 8: asm("movdqa %0, %%xmm8" : : "m"(*data)); break;
-	case 9: asm("movdqa %0, %%xmm9" : : "m"(*data)); break;
-	case 10: asm("movdqa %0, %%xmm10" : : "m"(*data)); break;
-	case 11: asm("movdqa %0, %%xmm11" : : "m"(*data)); break;
-	case 12: asm("movdqa %0, %%xmm12" : : "m"(*data)); break;
-	case 13: asm("movdqa %0, %%xmm13" : : "m"(*data)); break;
-	case 14: asm("movdqa %0, %%xmm14" : : "m"(*data)); break;
-	case 15: asm("movdqa %0, %%xmm15" : : "m"(*data)); break;
-#endif
-	default: BUG();
-	}
-	emulator_put_fpu();
-}
-
-static void read_mmx_reg(u64 *data, int reg)
-{
-	emulator_get_fpu();
-	switch (reg) {
-	case 0: asm("movq %%mm0, %0" : "=m"(*data)); break;
-	case 1: asm("movq %%mm1, %0" : "=m"(*data)); break;
-	case 2: asm("movq %%mm2, %0" : "=m"(*data)); break;
-	case 3: asm("movq %%mm3, %0" : "=m"(*data)); break;
-	case 4: asm("movq %%mm4, %0" : "=m"(*data)); break;
-	case 5: asm("movq %%mm5, %0" : "=m"(*data)); break;
-	case 6: asm("movq %%mm6, %0" : "=m"(*data)); break;
-	case 7: asm("movq %%mm7, %0" : "=m"(*data)); break;
-	default: BUG();
-	}
-	emulator_put_fpu();
-}
-
-static void write_mmx_reg(u64 *data, int reg)
-{
-	emulator_get_fpu();
-	switch (reg) {
-	case 0: asm("movq %0, %%mm0" : : "m"(*data)); break;
-	case 1: asm("movq %0, %%mm1" : : "m"(*data)); break;
-	case 2: asm("movq %0, %%mm2" : : "m"(*data)); break;
-	case 3: asm("movq %0, %%mm3" : : "m"(*data)); break;
-	case 4: asm("movq %0, %%mm4" : : "m"(*data)); break;
-	case 5: asm("movq %0, %%mm5" : : "m"(*data)); break;
-	case 6: asm("movq %0, %%mm6" : : "m"(*data)); break;
-	case 7: asm("movq %0, %%mm7" : : "m"(*data)); break;
-	default: BUG();
-	}
-	emulator_put_fpu();
-}
-
 static int em_fninit(struct x86_emulate_ctxt *ctxt)
 {
 	if (ctxt->ops->get_cr(ctxt, 0) & (X86_CR0_TS | X86_CR0_EM))
 		return emulate_nm(ctxt);
 
-	emulator_get_fpu();
+	kvm_fpu_get();
 	asm volatile("fninit");
-	emulator_put_fpu();
+	kvm_fpu_put();
 	return X86EMUL_CONTINUE;
 }
 
@@ -1201,9 +1099,9 @@ static int em_fnstcw(struct x86_emulate_ctxt *ctxt)
 	if (ctxt->ops->get_cr(ctxt, 0) & (X86_CR0_TS | X86_CR0_EM))
 		return emulate_nm(ctxt);
 
-	emulator_get_fpu();
+	kvm_fpu_get();
 	asm volatile("fnstcw %0": "+m"(fcw));
-	emulator_put_fpu();
+	kvm_fpu_put();
 
 	ctxt->dst.val = fcw;
 
@@ -1217,9 +1115,9 @@ static int em_fnstsw(struct x86_emulate_ctxt *ctxt)
 	if (ctxt->ops->get_cr(ctxt, 0) & (X86_CR0_TS | X86_CR0_EM))
 		return emulate_nm(ctxt);
 
-	emulator_get_fpu();
+	kvm_fpu_get();
 	asm volatile("fnstsw %0": "+m"(fsw));
-	emulator_put_fpu();
+	kvm_fpu_put();
 
 	ctxt->dst.val = fsw;
 
@@ -1238,7 +1136,7 @@ static void decode_register_operand(struct x86_emulate_ctxt *ctxt,
 		op->type = OP_XMM;
 		op->bytes = 16;
 		op->addr.xmm = reg;
-		read_sse_reg(&op->vec_val, reg);
+		kvm_read_sse_reg(reg, &op->vec_val);
 		return;
 	}
 	if (ctxt->d & Mmx) {
@@ -1289,7 +1187,7 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
 			op->type = OP_XMM;
 			op->bytes = 16;
 			op->addr.xmm = ctxt->modrm_rm;
-			read_sse_reg(&op->vec_val, ctxt->modrm_rm);
+			kvm_read_sse_reg(ctxt->modrm_rm, &op->vec_val);
 			return rc;
 		}
 		if (ctxt->d & Mmx) {
@@ -1866,10 +1764,10 @@ static int writeback(struct x86_emulate_ctxt *ctxt, struct operand *op)
 				       op->bytes * op->count);
 		break;
 	case OP_XMM:
-		write_sse_reg(&op->vec_val, op->addr.xmm);
+		kvm_write_sse_reg(op->addr.xmm, &op->vec_val);
 		break;
 	case OP_MM:
-		write_mmx_reg(&op->mm_val, op->addr.mm);
+		kvm_write_mmx_reg(op->addr.mm, &op->mm_val);
 		break;
 	case OP_NONE:
 		/* no writeback */
@@ -4124,11 +4022,11 @@ static int em_fxsave(struct x86_emulate_ctxt *ctxt)
 	if (rc != X86EMUL_CONTINUE)
 		return rc;
 
-	emulator_get_fpu();
+	kvm_fpu_get();
 
 	rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_state));
 
-	emulator_put_fpu();
+	kvm_fpu_put();
 
 	if (rc != X86EMUL_CONTINUE)
 		return rc;
@@ -4172,7 +4070,7 @@ static int em_fxrstor(struct x86_emulate_ctxt *ctxt)
 	if (rc != X86EMUL_CONTINUE)
 		return rc;
 
-	emulator_get_fpu();
+	kvm_fpu_get();
 
 	if (size < __fxstate_size(16)) {
 		rc = fxregs_fixup(&fx_state, size);
@@ -4189,7 +4087,7 @@ static int em_fxrstor(struct x86_emulate_ctxt *ctxt)
 		rc = asm_safe("fxrstor %[fx]", : [fx] "m"(fx_state));
 
 out:
-	emulator_put_fpu();
+	kvm_fpu_put();
 
 	return rc;
 }
@@ -5510,9 +5408,9 @@ static int flush_pending_x87_faults(struct x86_emulate_ctxt *ctxt)
 {
 	int rc;
 
-	emulator_get_fpu();
+	kvm_fpu_get();
 	rc = asm_safe("fwait");
-	emulator_put_fpu();
+	kvm_fpu_put();
 
 	if (unlikely(rc != X86EMUL_CONTINUE))
 		return emulate_exception(ctxt, MF_VECTOR, 0, false);
@@ -5523,7 +5421,7 @@ static int flush_pending_x87_faults(struct x86_emulate_ctxt *ctxt)
 static void fetch_possible_mmx_operand(struct operand *op)
 {
 	if (op->type == OP_MM)
-		read_mmx_reg(&op->mm_val, op->addr.mm);
+		kvm_read_mmx_reg(op->addr.mm, &op->mm_val);
 }
 
 static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop)
diff --git a/arch/x86/kvm/fpu.h b/arch/x86/kvm/fpu.h
new file mode 100644
index 000000000000..3ba12888bf66
--- /dev/null
+++ b/arch/x86/kvm/fpu.h
@@ -0,0 +1,140 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __KVM_FPU_H_
+#define __KVM_FPU_H_
+
+#include <asm/fpu/api.h>
+
+typedef u32		__attribute__((vector_size(16))) sse128_t;
+#define __sse128_u	union { sse128_t vec; u64 as_u64[2]; u32 as_u32[4]; }
+#define sse128_lo(x)	({ __sse128_u t; t.vec = x; t.as_u64[0]; })
+#define sse128_hi(x)	({ __sse128_u t; t.vec = x; t.as_u64[1]; })
+#define sse128_l0(x)	({ __sse128_u t; t.vec = x; t.as_u32[0]; })
+#define sse128_l1(x)	({ __sse128_u t; t.vec = x; t.as_u32[1]; })
+#define sse128_l2(x)	({ __sse128_u t; t.vec = x; t.as_u32[2]; })
+#define sse128_l3(x)	({ __sse128_u t; t.vec = x; t.as_u32[3]; })
+#define sse128(lo, hi)	({ __sse128_u t; t.as_u64[0] = lo; t.as_u64[1] = hi; t.vec; })
+
+static inline void _kvm_read_sse_reg(int reg, sse128_t *data)
+{
+	switch (reg) {
+	case 0: asm("movdqa %%xmm0, %0" : "=m"(*data)); break;
+	case 1: asm("movdqa %%xmm1, %0" : "=m"(*data)); break;
+	case 2: asm("movdqa %%xmm2, %0" : "=m"(*data)); break;
+	case 3: asm("movdqa %%xmm3, %0" : "=m"(*data)); break;
+	case 4: asm("movdqa %%xmm4, %0" : "=m"(*data)); break;
+	case 5: asm("movdqa %%xmm5, %0" : "=m"(*data)); break;
+	case 6: asm("movdqa %%xmm6, %0" : "=m"(*data)); break;
+	case 7: asm("movdqa %%xmm7, %0" : "=m"(*data)); break;
+#ifdef CONFIG_X86_64
+	case 8: asm("movdqa %%xmm8, %0" : "=m"(*data)); break;
+	case 9: asm("movdqa %%xmm9, %0" : "=m"(*data)); break;
+	case 10: asm("movdqa %%xmm10, %0" : "=m"(*data)); break;
+	case 11: asm("movdqa %%xmm11, %0" : "=m"(*data)); break;
+	case 12: asm("movdqa %%xmm12, %0" : "=m"(*data)); break;
+	case 13: asm("movdqa %%xmm13, %0" : "=m"(*data)); break;
+	case 14: asm("movdqa %%xmm14, %0" : "=m"(*data)); break;
+	case 15: asm("movdqa %%xmm15, %0" : "=m"(*data)); break;
+#endif
+	default: BUG();
+	}
+}
+
+static inline void _kvm_write_sse_reg(int reg, const sse128_t *data)
+{
+	switch (reg) {
+	case 0: asm("movdqa %0, %%xmm0" : : "m"(*data)); break;
+	case 1: asm("movdqa %0, %%xmm1" : : "m"(*data)); break;
+	case 2: asm("movdqa %0, %%xmm2" : : "m"(*data)); break;
+	case 3: asm("movdqa %0, %%xmm3" : : "m"(*data)); break;
+	case 4: asm("movdqa %0, %%xmm4" : : "m"(*data)); break;
+	case 5: asm("movdqa %0, %%xmm5" : : "m"(*data)); break;
+	case 6: asm("movdqa %0, %%xmm6" : : "m"(*data)); break;
+	case 7: asm("movdqa %0, %%xmm7" : : "m"(*data)); break;
+#ifdef CONFIG_X86_64
+	case 8: asm("movdqa %0, %%xmm8" : : "m"(*data)); break;
+	case 9: asm("movdqa %0, %%xmm9" : : "m"(*data)); break;
+	case 10: asm("movdqa %0, %%xmm10" : : "m"(*data)); break;
+	case 11: asm("movdqa %0, %%xmm11" : : "m"(*data)); break;
+	case 12: asm("movdqa %0, %%xmm12" : : "m"(*data)); break;
+	case 13: asm("movdqa %0, %%xmm13" : : "m"(*data)); break;
+	case 14: asm("movdqa %0, %%xmm14" : : "m"(*data)); break;
+	case 15: asm("movdqa %0, %%xmm15" : : "m"(*data)); break;
+#endif
+	default: BUG();
+	}
+}
+
+static inline void _kvm_read_mmx_reg(int reg, u64 *data)
+{
+	switch (reg) {
+	case 0: asm("movq %%mm0, %0" : "=m"(*data)); break;
+	case 1: asm("movq %%mm1, %0" : "=m"(*data)); break;
+	case 2: asm("movq %%mm2, %0" : "=m"(*data)); break;
+	case 3: asm("movq %%mm3, %0" : "=m"(*data)); break;
+	case 4: asm("movq %%mm4, %0" : "=m"(*data)); break;
+	case 5: asm("movq %%mm5, %0" : "=m"(*data)); break;
+	case 6: asm("movq %%mm6, %0" : "=m"(*data)); break;
+	case 7: asm("movq %%mm7, %0" : "=m"(*data)); break;
+	default: BUG();
+	}
+}
+
+static inline void _kvm_write_mmx_reg(int reg, const u64 *data)
+{
+	switch (reg) {
+	case 0: asm("movq %0, %%mm0" : : "m"(*data)); break;
+	case 1: asm("movq %0, %%mm1" : : "m"(*data)); break;
+	case 2: asm("movq %0, %%mm2" : : "m"(*data)); break;
+	case 3: asm("movq %0, %%mm3" : : "m"(*data)); break;
+	case 4: asm("movq %0, %%mm4" : : "m"(*data)); break;
+	case 5: asm("movq %0, %%mm5" : : "m"(*data)); break;
+	case 6: asm("movq %0, %%mm6" : : "m"(*data)); break;
+	case 7: asm("movq %0, %%mm7" : : "m"(*data)); break;
+	default: BUG();
+	}
+}
+
+static inline void kvm_fpu_get(void)
+{
+	fpregs_lock();
+
+	fpregs_assert_state_consistent();
+	if (test_thread_flag(TIF_NEED_FPU_LOAD))
+		switch_fpu_return();
+}
+
+static inline void kvm_fpu_put(void)
+{
+	fpregs_unlock();
+}
+
+static inline void kvm_read_sse_reg(int reg, sse128_t *data)
+{
+	kvm_fpu_get();
+	_kvm_read_sse_reg(reg, data);
+	kvm_fpu_put();
+}
+
+static inline void kvm_write_sse_reg(int reg, const sse128_t *data)
+{
+	kvm_fpu_get();
+	_kvm_write_sse_reg(reg, data);
+	kvm_fpu_put();
+}
+
+static inline void kvm_read_mmx_reg(int reg, u64 *data)
+{
+	kvm_fpu_get();
+	_kvm_read_mmx_reg(reg, data);
+	kvm_fpu_put();
+}
+
+static inline void kvm_write_mmx_reg(int reg, const u64 *data)
+{
+	kvm_fpu_get();
+	_kvm_write_mmx_reg(reg, data);
+	kvm_fpu_put();
+}
+
+#endif
-- 
2.17.1




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

[PATCH 2/4] KVM: hyper-v: Collect hypercall params into struct

[Siddharth Chandrasekaran]

As of now there are 7 parameters (and flags) that are used in various
hyper-v hypercall handlers. There are 6 more input/output parameters
passed from XMM registers which are to be added in an upcoming patch.

To make passing arguments to the handlers more readable, capture all
these parameters into a single structure.

Cc: Alexander Graf <graf@amazon.com>
Cc: Evgeny Iakovlev <eyakovl@amazon.de>
Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
---
 arch/x86/kvm/hyperv.c | 147 +++++++++++++++++++++++-------------------
 1 file changed, 79 insertions(+), 68 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index f98370a39936..8f6babd1ea0d 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1623,7 +1623,18 @@ static __always_inline unsigned long *sparse_set_to_vcpu_mask(
 	return vcpu_bitmap;
 }
 
-static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, u64 ingpa, u16 rep_cnt, bool ex)
+struct kvm_hv_hcall {
+	u64 param;
+	u64 ingpa;
+	u64 outgpa;
+	u16 code;
+	u16 rep_cnt;
+	u16 rep_idx;
+	bool fast;
+	bool rep;
+};
+
+static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool ex)
 {
 	struct kvm *kvm = vcpu->kvm;
 	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
@@ -1638,7 +1649,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, u64 ingpa, u16 rep_cnt, bool
 	bool all_cpus;
 
 	if (!ex) {
-		if (unlikely(kvm_read_guest(kvm, ingpa, &flush, sizeof(flush))))
+		if (unlikely(kvm_read_guest(kvm, hc->ingpa, &flush, sizeof(flush))))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
 
 		trace_kvm_hv_flush_tlb(flush.processor_mask,
@@ -1657,7 +1668,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, u64 ingpa, u16 rep_cnt, bool
 		all_cpus = (flush.flags & HV_FLUSH_ALL_PROCESSORS) ||
 			flush.processor_mask == 0;
 	} else {
-		if (unlikely(kvm_read_guest(kvm, ingpa, &flush_ex,
+		if (unlikely(kvm_read_guest(kvm, hc->ingpa, &flush_ex,
 					    sizeof(flush_ex))))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
 
@@ -1679,8 +1690,8 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, u64 ingpa, u16 rep_cnt, bool
 
 		if (!all_cpus &&
 		    kvm_read_guest(kvm,
-				   ingpa + offsetof(struct hv_tlb_flush_ex,
-						    hv_vp_set.bank_contents),
+				   hc->ingpa + offsetof(struct hv_tlb_flush_ex,
+							hv_vp_set.bank_contents),
 				   sparse_banks,
 				   sparse_banks_len))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
@@ -1700,9 +1711,9 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, u64 ingpa, u16 rep_cnt, bool
 				    NULL, vcpu_mask, &hv_vcpu->tlb_flush);
 
 ret_success:
-	/* We always do full TLB flush, set rep_done = rep_cnt. */
+	/* We always do full TLB flush, set rep_done = hc->rep_cnt. */
 	return (u64)HV_STATUS_SUCCESS |
-		((u64)rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
+		((u64)hc->rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
 }
 
 static void kvm_send_ipi_to_many(struct kvm *kvm, u32 vector,
@@ -1724,8 +1735,7 @@ static void kvm_send_ipi_to_many(struct kvm *kvm, u32 vector,
 	}
 }
 
-static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, u64 ingpa, u64 outgpa,
-			   bool ex, bool fast)
+static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool ex)
 {
 	struct kvm *kvm = vcpu->kvm;
 	struct hv_send_ipi_ex send_ipi_ex;
@@ -1740,25 +1750,25 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, u64 ingpa, u64 outgpa,
 	bool all_cpus;
 
 	if (!ex) {
-		if (!fast) {
-			if (unlikely(kvm_read_guest(kvm, ingpa, &send_ipi,
+		if (!hc->fast) {
+			if (unlikely(kvm_read_guest(kvm, hc->ingpa, &send_ipi,
 						    sizeof(send_ipi))))
 				return HV_STATUS_INVALID_HYPERCALL_INPUT;
 			sparse_banks[0] = send_ipi.cpu_mask;
 			vector = send_ipi.vector;
 		} else {
 			/* 'reserved' part of hv_send_ipi should be 0 */
-			if (unlikely(ingpa >> 32 != 0))
+			if (unlikely(hc->ingpa >> 32 != 0))
 				return HV_STATUS_INVALID_HYPERCALL_INPUT;
-			sparse_banks[0] = outgpa;
-			vector = (u32)ingpa;
+			sparse_banks[0] = hc->outgpa;
+			vector = (u32)hc->ingpa;
 		}
 		all_cpus = false;
 		valid_bank_mask = BIT_ULL(0);
 
 		trace_kvm_hv_send_ipi(vector, sparse_banks[0]);
 	} else {
-		if (unlikely(kvm_read_guest(kvm, ingpa, &send_ipi_ex,
+		if (unlikely(kvm_read_guest(kvm, hc->ingpa, &send_ipi_ex,
 					    sizeof(send_ipi_ex))))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
 
@@ -1778,8 +1788,8 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, u64 ingpa, u64 outgpa,
 
 		if (!all_cpus &&
 		    kvm_read_guest(kvm,
-				   ingpa + offsetof(struct hv_send_ipi_ex,
-						    vp_set.bank_contents),
+				   hc->ingpa + offsetof(struct hv_send_ipi_ex,
+							vp_set.bank_contents),
 				   sparse_banks,
 				   sparse_banks_len))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
@@ -1839,20 +1849,21 @@ static int kvm_hv_hypercall_complete_userspace(struct kvm_vcpu *vcpu)
 	return kvm_hv_hypercall_complete(vcpu, vcpu->run->hyperv.u.hcall.result);
 }
 
-static u16 kvm_hvcall_signal_event(struct kvm_vcpu *vcpu, bool fast, u64 param)
+static u16 kvm_hvcall_signal_event(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
 {
 	struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);
 	struct eventfd_ctx *eventfd;
 
-	if (unlikely(!fast)) {
+	if (unlikely(!hc->fast)) {
 		int ret;
-		gpa_t gpa = param;
+		gpa_t gpa = hc->ingpa;
 
-		if ((gpa & (__alignof__(param) - 1)) ||
-		    offset_in_page(gpa) + sizeof(param) > PAGE_SIZE)
+		if ((gpa & (__alignof__(hc->ingpa) - 1)) ||
+		    offset_in_page(gpa) + sizeof(hc->ingpa) > PAGE_SIZE)
 			return HV_STATUS_INVALID_ALIGNMENT;
 
-		ret = kvm_vcpu_read_guest(vcpu, gpa, &param, sizeof(param));
+		ret = kvm_vcpu_read_guest(vcpu, gpa,
+					  &hc->ingpa, sizeof(hc->ingpa));
 		if (ret < 0)
 			return HV_STATUS_INVALID_ALIGNMENT;
 	}
@@ -1862,15 +1873,15 @@ static u16 kvm_hvcall_signal_event(struct kvm_vcpu *vcpu, bool fast, u64 param)
 	 * have no use for it, and in all known usecases it is zero, so just
 	 * report lookup failure if it isn't.
 	 */
-	if (param & 0xffff00000000ULL)
+	if (hc->ingpa & 0xffff00000000ULL)
 		return HV_STATUS_INVALID_PORT_ID;
 	/* remaining bits are reserved-zero */
-	if (param & ~KVM_HYPERV_CONN_ID_MASK)
+	if (hc->ingpa & ~KVM_HYPERV_CONN_ID_MASK)
 		return HV_STATUS_INVALID_HYPERCALL_INPUT;
 
 	/* the eventfd is protected by vcpu->kvm->srcu, but conn_to_evt isn't */
 	rcu_read_lock();
-	eventfd = idr_find(&hv->conn_to_evt, param);
+	eventfd = idr_find(&hv->conn_to_evt, hc->ingpa);
 	rcu_read_unlock();
 	if (!eventfd)
 		return HV_STATUS_INVALID_PORT_ID;
@@ -1881,9 +1892,8 @@ static u16 kvm_hvcall_signal_event(struct kvm_vcpu *vcpu, bool fast, u64 param)
 
 int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 {
-	u64 param, ingpa, outgpa, ret = HV_STATUS_SUCCESS;
-	uint16_t code, rep_idx, rep_cnt;
-	bool fast, rep;
+	struct kvm_hv_hcall hc;
+	u64 ret = HV_STATUS_SUCCESS;
 
 	/*
 	 * hypercall generates UD from non zero cpl and real mode
@@ -1896,104 +1906,105 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 
 #ifdef CONFIG_X86_64
 	if (is_64_bit_mode(vcpu)) {
-		param = kvm_rcx_read(vcpu);
-		ingpa = kvm_rdx_read(vcpu);
-		outgpa = kvm_r8_read(vcpu);
+		hc.param = kvm_rcx_read(vcpu);
+		hc.ingpa = kvm_rdx_read(vcpu);
+		hc.outgpa = kvm_r8_read(vcpu);
 	} else
 #endif
 	{
-		param = ((u64)kvm_rdx_read(vcpu) << 32) |
-			(kvm_rax_read(vcpu) & 0xffffffff);
-		ingpa = ((u64)kvm_rbx_read(vcpu) << 32) |
-			(kvm_rcx_read(vcpu) & 0xffffffff);
-		outgpa = ((u64)kvm_rdi_read(vcpu) << 32) |
-			(kvm_rsi_read(vcpu) & 0xffffffff);
+		hc.param = ((u64)kvm_rdx_read(vcpu) << 32) |
+			    (kvm_rax_read(vcpu) & 0xffffffff);
+		hc.ingpa = ((u64)kvm_rbx_read(vcpu) << 32) |
+			    (kvm_rcx_read(vcpu) & 0xffffffff);
+		hc.outgpa = ((u64)kvm_rdi_read(vcpu) << 32) |
+			     (kvm_rsi_read(vcpu) & 0xffffffff);
 	}
 
-	code = param & 0xffff;
-	fast = !!(param & HV_HYPERCALL_FAST_BIT);
-	rep_cnt = (param >> HV_HYPERCALL_REP_COMP_OFFSET) & 0xfff;
-	rep_idx = (param >> HV_HYPERCALL_REP_START_OFFSET) & 0xfff;
-	rep = !!(rep_cnt || rep_idx);
+	hc.code = hc.param & 0xffff;
+	hc.fast = !!(hc.param & HV_HYPERCALL_FAST_BIT);
+	hc.rep_cnt = (hc.param >> HV_HYPERCALL_REP_COMP_OFFSET) & 0xfff;
+	hc.rep_idx = (hc.param >> HV_HYPERCALL_REP_START_OFFSET) & 0xfff;
+	hc.rep = !!(hc.rep_cnt || hc.rep_idx);
 
-	trace_kvm_hv_hypercall(code, fast, rep_cnt, rep_idx, ingpa, outgpa);
+	trace_kvm_hv_hypercall(hc.code, hc.fast, hc.rep_cnt, hc.rep_idx,
+			       hc.ingpa, hc.outgpa);
 
-	switch (code) {
+	switch (hc.code) {
 	case HVCALL_NOTIFY_LONG_SPIN_WAIT:
-		if (unlikely(rep)) {
+		if (unlikely(hc.rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
 		kvm_vcpu_on_spin(vcpu, true);
 		break;
 	case HVCALL_SIGNAL_EVENT:
-		if (unlikely(rep)) {
+		if (unlikely(hc.rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
-		ret = kvm_hvcall_signal_event(vcpu, fast, ingpa);
+		ret = kvm_hvcall_signal_event(vcpu, &hc);
 		if (ret != HV_STATUS_INVALID_PORT_ID)
 			break;
 		fallthrough;	/* maybe userspace knows this conn_id */
 	case HVCALL_POST_MESSAGE:
 		/* don't bother userspace if it has no way to handle it */
-		if (unlikely(rep || !to_hv_synic(vcpu)->active)) {
+		if (unlikely(hc.rep || !to_hv_synic(vcpu)->active)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
 		vcpu->run->exit_reason = KVM_EXIT_HYPERV;
 		vcpu->run->hyperv.type = KVM_EXIT_HYPERV_HCALL;
-		vcpu->run->hyperv.u.hcall.input = param;
-		vcpu->run->hyperv.u.hcall.params[0] = ingpa;
-		vcpu->run->hyperv.u.hcall.params[1] = outgpa;
+		vcpu->run->hyperv.u.hcall.input = hc.param;
+		vcpu->run->hyperv.u.hcall.params[0] = hc.ingpa;
+		vcpu->run->hyperv.u.hcall.params[1] = hc.outgpa;
 		vcpu->arch.complete_userspace_io =
 				kvm_hv_hypercall_complete_userspace;
 		return 0;
 	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
-		if (unlikely(fast || !rep_cnt || rep_idx)) {
+		if (unlikely(hc.fast || !hc.rep_cnt || hc.rep_idx)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
-		ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false);
+		ret = kvm_hv_flush_tlb(vcpu, &hc, false);
 		break;
 	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
-		if (unlikely(fast || rep)) {
+		if (unlikely(hc.fast || hc.rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
-		ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false);
+		ret = kvm_hv_flush_tlb(vcpu, &hc, false);
 		break;
 	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
-		if (unlikely(fast || !rep_cnt || rep_idx)) {
+		if (unlikely(hc.fast || !hc.rep_cnt || hc.rep_idx)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
-		ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true);
+		ret = kvm_hv_flush_tlb(vcpu, &hc, true);
 		break;
 	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
-		if (unlikely(fast || rep)) {
+		if (unlikely(hc.fast || hc.rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
-		ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true);
+		ret = kvm_hv_flush_tlb(vcpu, &hc, true);
 		break;
 	case HVCALL_SEND_IPI:
-		if (unlikely(rep)) {
+		if (unlikely(hc.rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
-		ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, false, fast);
+		ret = kvm_hv_send_ipi(vcpu, &hc, false);
 		break;
 	case HVCALL_SEND_IPI_EX:
-		if (unlikely(fast || rep)) {
+		if (unlikely(hc.fast || hc.rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
-		ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, true, false);
+		ret = kvm_hv_send_ipi(vcpu, &hc, true);
 		break;
 	case HVCALL_POST_DEBUG_DATA:
 	case HVCALL_RETRIEVE_DEBUG_DATA:
-		if (unlikely(fast)) {
+		if (unlikely(hc.fast)) {
 			ret = HV_STATUS_INVALID_PARAMETER;
 			break;
 		}
@@ -2012,9 +2023,9 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 		}
 		vcpu->run->exit_reason = KVM_EXIT_HYPERV;
 		vcpu->run->hyperv.type = KVM_EXIT_HYPERV_HCALL;
-		vcpu->run->hyperv.u.hcall.input = param;
-		vcpu->run->hyperv.u.hcall.params[0] = ingpa;
-		vcpu->run->hyperv.u.hcall.params[1] = outgpa;
+		vcpu->run->hyperv.u.hcall.input = hc.param;
+		vcpu->run->hyperv.u.hcall.params[0] = hc.ingpa;
+		vcpu->run->hyperv.u.hcall.params[1] = hc.outgpa;
 		vcpu->arch.complete_userspace_io =
 				kvm_hv_hypercall_complete_userspace;
 		return 0;
-- 
2.17.1




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

[PATCH 3/4] KVM: x86: kvm_hv_flush_tlb use inputs from XMM registers

[Siddharth Chandrasekaran]

Hyper-V supports the use of XMM registers to perform fast hypercalls.
This allows guests to take advantage of the improved performance of the
fast hypercall interface even though a hypercall may require more than
(the current maximum of) two input registers.

The XMM fast hypercall interface uses six additional XMM registers (XMM0
to XMM5) to allow the guest to pass an input parameter block of up to
112 bytes. Hyper-V can also return data back to the guest in the
remaining XMM registers that are not used by the current hypercall.

Add framework to read/write to XMM registers in kvm_hv_hypercall() and
use the additional hypercall inputs from XMM registers in
kvm_hv_flush_tlb() when possible.

Cc: Alexander Graf <graf@amazon.com>
Co-developed-by: Evgeny Iakovlev <eyakovl@amazon.de>
Signed-off-by: Evgeny Iakovlev <eyakovl@amazon.de>
Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
---
 arch/x86/kvm/hyperv.c | 109 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 90 insertions(+), 19 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 8f6babd1ea0d..bf2f86f263f1 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -36,6 +36,7 @@
 
 #include "trace.h"
 #include "irq.h"
+#include "fpu.h"
 
 /* "Hv#1" signature */
 #define HYPERV_CPUID_SIGNATURE_EAX 0x31237648
@@ -1623,6 +1624,8 @@ static __always_inline unsigned long *sparse_set_to_vcpu_mask(
 	return vcpu_bitmap;
 }
 
+#define KVM_HV_HYPERCALL_MAX_XMM_REGISTERS  6
+
 struct kvm_hv_hcall {
 	u64 param;
 	u64 ingpa;
@@ -1632,10 +1635,14 @@ struct kvm_hv_hcall {
 	u16 rep_idx;
 	bool fast;
 	bool rep;
+	sse128_t xmm[KVM_HV_HYPERCALL_MAX_XMM_REGISTERS];
+	bool xmm_dirty;
 };
 
 static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool ex)
 {
+	int i, j;
+	gpa_t gpa;
 	struct kvm *kvm = vcpu->kvm;
 	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
 	struct hv_tlb_flush_ex flush_ex;
@@ -1649,8 +1656,15 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
 	bool all_cpus;
 
 	if (!ex) {
-		if (unlikely(kvm_read_guest(kvm, hc->ingpa, &flush, sizeof(flush))))
-			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+		if (hc->fast) {
+			flush.address_space = hc->ingpa;
+			flush.flags = hc->outgpa;
+			flush.processor_mask = sse128_lo(hc->xmm[0]);
+		} else {
+			if (unlikely(kvm_read_guest(kvm, hc->ingpa,
+						    &flush, sizeof(flush))))
+				return HV_STATUS_INVALID_HYPERCALL_INPUT;
+		}
 
 		trace_kvm_hv_flush_tlb(flush.processor_mask,
 				       flush.address_space, flush.flags);
@@ -1668,9 +1682,16 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
 		all_cpus = (flush.flags & HV_FLUSH_ALL_PROCESSORS) ||
 			flush.processor_mask == 0;
 	} else {
-		if (unlikely(kvm_read_guest(kvm, hc->ingpa, &flush_ex,
-					    sizeof(flush_ex))))
-			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+		if (hc->fast) {
+			flush_ex.address_space = hc->ingpa;
+			flush_ex.flags = hc->outgpa;
+			memcpy(&flush_ex.hv_vp_set,
+			       &hc->xmm[0], sizeof(hc->xmm[0]));
+		} else {
+			if (unlikely(kvm_read_guest(kvm, hc->ingpa, &flush_ex,
+						    sizeof(flush_ex))))
+				return HV_STATUS_INVALID_HYPERCALL_INPUT;
+		}
 
 		trace_kvm_hv_flush_tlb_ex(flush_ex.hv_vp_set.valid_bank_mask,
 					  flush_ex.hv_vp_set.format,
@@ -1681,20 +1702,29 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
 		all_cpus = flush_ex.hv_vp_set.format !=
 			HV_GENERIC_SET_SPARSE_4K;
 
-		sparse_banks_len =
-			bitmap_weight((unsigned long *)&valid_bank_mask, 64) *
-			sizeof(sparse_banks[0]);
+		sparse_banks_len = bitmap_weight((unsigned long *)&valid_bank_mask, 64);
 
 		if (!sparse_banks_len && !all_cpus)
 			goto ret_success;
 
-		if (!all_cpus &&
-		    kvm_read_guest(kvm,
-				   hc->ingpa + offsetof(struct hv_tlb_flush_ex,
-							hv_vp_set.bank_contents),
-				   sparse_banks,
-				   sparse_banks_len))
-			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+		if (!all_cpus) {
+			if (hc->fast) {
+				if (sparse_banks_len > KVM_HV_HYPERCALL_MAX_XMM_REGISTERS - 1)
+					return HV_STATUS_INVALID_HYPERCALL_INPUT;
+				for (i = 0, j = 1; i < sparse_banks_len; i += 2, j++) {
+					sparse_banks[i + 0] = sse128_lo(hc->xmm[j]);
+					sparse_banks[i + 1] = sse128_hi(hc->xmm[j]);
+				}
+			} else {
+				gpa = hc->ingpa;
+				gpa += offsetof(struct hv_tlb_flush_ex,
+						hv_vp_set.bank_contents);
+				if (unlikely(kvm_read_guest(kvm, gpa, sparse_banks,
+							    sparse_banks_len *
+							    sizeof(sparse_banks[0]))))
+					return HV_STATUS_INVALID_HYPERCALL_INPUT;
+			}
+		}
 	}
 
 	cpumask_clear(&hv_vcpu->tlb_flush);
@@ -1890,6 +1920,41 @@ static u16 kvm_hvcall_signal_event(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *h
 	return HV_STATUS_SUCCESS;
 }
 
+static bool is_xmm_fast_hypercall(struct kvm_hv_hcall *hc)
+{
+	switch (hc->code) {
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
+		return true;
+	}
+
+	return false;
+}
+
+static inline void kvm_hv_hypercall_read_xmm(struct kvm_hv_hcall *hc)
+{
+	int reg;
+
+	kvm_fpu_get();
+	for (reg = 0; reg < KVM_HV_HYPERCALL_MAX_XMM_REGISTERS; reg++)
+		_kvm_read_sse_reg(reg, &hc->xmm[reg]);
+	kvm_fpu_put();
+	hc->xmm_dirty = false;
+}
+
+static inline void kvm_hv_hypercall_write_xmm(struct kvm_hv_hcall *hc)
+{
+	int reg;
+
+	kvm_fpu_get();
+	for (reg = 0; reg < KVM_HV_HYPERCALL_MAX_XMM_REGISTERS; reg++)
+		_kvm_write_sse_reg(reg, &hc->xmm[reg]);
+	kvm_fpu_put();
+	hc->xmm_dirty = false;
+}
+
 int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 {
 	struct kvm_hv_hcall hc;
@@ -1926,6 +1991,9 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 	hc.rep_idx = (hc.param >> HV_HYPERCALL_REP_START_OFFSET) & 0xfff;
 	hc.rep = !!(hc.rep_cnt || hc.rep_idx);
 
+	if (is_xmm_fast_hypercall(&hc))
+		kvm_hv_hypercall_read_xmm(&hc);
+
 	trace_kvm_hv_hypercall(hc.code, hc.fast, hc.rep_cnt, hc.rep_idx,
 			       hc.ingpa, hc.outgpa);
 
@@ -1961,28 +2029,28 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 				kvm_hv_hypercall_complete_userspace;
 		return 0;
 	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
-		if (unlikely(hc.fast || !hc.rep_cnt || hc.rep_idx)) {
+		if (unlikely(!hc.rep_cnt || hc.rep_idx)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
 		ret = kvm_hv_flush_tlb(vcpu, &hc, false);
 		break;
 	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
-		if (unlikely(hc.fast || hc.rep)) {
+		if (unlikely(hc.rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
 		ret = kvm_hv_flush_tlb(vcpu, &hc, false);
 		break;
 	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
-		if (unlikely(hc.fast || !hc.rep_cnt || hc.rep_idx)) {
+		if (unlikely(!hc.rep_cnt || hc.rep_idx)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
 		ret = kvm_hv_flush_tlb(vcpu, &hc, true);
 		break;
 	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
-		if (unlikely(hc.fast || hc.rep)) {
+		if (unlikely(hc.rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
@@ -2035,6 +2103,9 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 		break;
 	}
 
+	if (hc.xmm_dirty)
+		kvm_hv_hypercall_write_xmm(&hc);
+
 	return kvm_hv_hypercall_complete(vcpu, ret);
 }
 
-- 
2.17.1




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

[PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Siddharth Chandrasekaran]

Now that all extant hypercalls that can use XMM registers (based on
spec) for input/outputs are patched to support them, we can start
advertising this feature to guests.

Cc: Alexander Graf <graf@amazon.com>
Cc: Evgeny Iakovlev <eyakovl@amazon.de>
Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
---
 arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
 arch/x86/kvm/hyperv.c              | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index e6cd3fee562b..1f160ef60509 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -49,10 +49,10 @@
 /* Support for physical CPU dynamic partitioning events is available*/
 #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE	BIT(3)
 /*
- * Support for passing hypercall input parameter block via XMM
+ * Support for passing hypercall input and output parameter block via XMM
  * registers is available
  */
-#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE		BIT(4)
+#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE		BIT(4) | BIT(15)
 /* Support for a virtual guest idle state is available */
 #define HV_X64_GUEST_IDLE_STATE_AVAILABLE		BIT(5)
 /* Frequency MSRs available */
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index bf2f86f263f1..dd462c1d641d 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2254,6 +2254,7 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
 			ent->ebx |= HV_POST_MESSAGES;
 			ent->ebx |= HV_SIGNAL_EVENTS;
 
+			ent->edx |= HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE;
 			ent->edx |= HV_FEATURE_FREQUENCY_MSRS_AVAILABLE;
 			ent->edx |= HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;
 
-- 
2.17.1




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

Re: [PATCH 3/4] KVM: x86: kvm_hv_flush_tlb use inputs from XMM registers

[Vitaly Kuznetsov]

Siddharth Chandrasekaran <sidcha@amazon.de> writes:

> Hyper-V supports the use of XMM registers to perform fast hypercalls.
> This allows guests to take advantage of the improved performance of the
> fast hypercall interface even though a hypercall may require more than
> (the current maximum of) two input registers.
>
> The XMM fast hypercall interface uses six additional XMM registers (XMM0
> to XMM5) to allow the guest to pass an input parameter block of up to
> 112 bytes. Hyper-V can also return data back to the guest in the
> remaining XMM registers that are not used by the current hypercall.
>
> Add framework to read/write to XMM registers in kvm_hv_hypercall() and
> use the additional hypercall inputs from XMM registers in
> kvm_hv_flush_tlb() when possible.
>
> Cc: Alexander Graf <graf@amazon.com>
> Co-developed-by: Evgeny Iakovlev <eyakovl@amazon.de>
> Signed-off-by: Evgeny Iakovlev <eyakovl@amazon.de>
> Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
> ---
>  arch/x86/kvm/hyperv.c | 109 ++++++++++++++++++++++++++++++++++--------
>  1 file changed, 90 insertions(+), 19 deletions(-)
>
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index 8f6babd1ea0d..bf2f86f263f1 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -36,6 +36,7 @@
>  
>  #include "trace.h"
>  #include "irq.h"
> +#include "fpu.h"
>  
>  /* "Hv#1" signature */
>  #define HYPERV_CPUID_SIGNATURE_EAX 0x31237648
> @@ -1623,6 +1624,8 @@ static __always_inline unsigned long *sparse_set_to_vcpu_mask(
>  	return vcpu_bitmap;
>  }
>  
> +#define KVM_HV_HYPERCALL_MAX_XMM_REGISTERS  6
> +
>  struct kvm_hv_hcall {
>  	u64 param;
>  	u64 ingpa;
> @@ -1632,10 +1635,14 @@ struct kvm_hv_hcall {
>  	u16 rep_idx;
>  	bool fast;
>  	bool rep;
> +	sse128_t xmm[KVM_HV_HYPERCALL_MAX_XMM_REGISTERS];
> +	bool xmm_dirty;
>  };
>  
>  static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool ex)
>  {
> +	int i, j;
> +	gpa_t gpa;
>  	struct kvm *kvm = vcpu->kvm;
>  	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
>  	struct hv_tlb_flush_ex flush_ex;
> @@ -1649,8 +1656,15 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
>  	bool all_cpus;
>  
>  	if (!ex) {
> -		if (unlikely(kvm_read_guest(kvm, hc->ingpa, &flush, sizeof(flush))))
> -			return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +		if (hc->fast) {
> +			flush.address_space = hc->ingpa;
> +			flush.flags = hc->outgpa;
> +			flush.processor_mask = sse128_lo(hc->xmm[0]);
> +		} else {
> +			if (unlikely(kvm_read_guest(kvm, hc->ingpa,
> +						    &flush, sizeof(flush))))
> +				return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +		}
>  
>  		trace_kvm_hv_flush_tlb(flush.processor_mask,
>  				       flush.address_space, flush.flags);
> @@ -1668,9 +1682,16 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
>  		all_cpus = (flush.flags & HV_FLUSH_ALL_PROCESSORS) ||
>  			flush.processor_mask == 0;
>  	} else {
> -		if (unlikely(kvm_read_guest(kvm, hc->ingpa, &flush_ex,
> -					    sizeof(flush_ex))))
> -			return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +		if (hc->fast) {
> +			flush_ex.address_space = hc->ingpa;
> +			flush_ex.flags = hc->outgpa;
> +			memcpy(&flush_ex.hv_vp_set,
> +			       &hc->xmm[0], sizeof(hc->xmm[0]));
> +		} else {
> +			if (unlikely(kvm_read_guest(kvm, hc->ingpa, &flush_ex,
> +						    sizeof(flush_ex))))
> +				return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +		}
>  
>  		trace_kvm_hv_flush_tlb_ex(flush_ex.hv_vp_set.valid_bank_mask,
>  					  flush_ex.hv_vp_set.format,
> @@ -1681,20 +1702,29 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
>  		all_cpus = flush_ex.hv_vp_set.format !=
>  			HV_GENERIC_SET_SPARSE_4K;
>  
> -		sparse_banks_len =
> -			bitmap_weight((unsigned long *)&valid_bank_mask, 64) *
> -			sizeof(sparse_banks[0]);
> +		sparse_banks_len = bitmap_weight((unsigned long *)&valid_bank_mask, 64);
>  
>  		if (!sparse_banks_len && !all_cpus)
>  			goto ret_success;
>  
> -		if (!all_cpus &&
> -		    kvm_read_guest(kvm,
> -				   hc->ingpa + offsetof(struct hv_tlb_flush_ex,
> -							hv_vp_set.bank_contents),
> -				   sparse_banks,
> -				   sparse_banks_len))
> -			return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +		if (!all_cpus) {
> +			if (hc->fast) {
> +				if (sparse_banks_len > KVM_HV_HYPERCALL_MAX_XMM_REGISTERS - 1)
> +					return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +				for (i = 0, j = 1; i < sparse_banks_len; i += 2, j++) {
> +					sparse_banks[i + 0] = sse128_lo(hc->xmm[j]);
> +					sparse_banks[i + 1] = sse128_hi(hc->xmm[j]);
> +				}
> +			} else {
> +				gpa = hc->ingpa;
> +				gpa += offsetof(struct hv_tlb_flush_ex,
> +						hv_vp_set.bank_contents);
> +				if (unlikely(kvm_read_guest(kvm, gpa, sparse_banks,
> +							    sparse_banks_len *
> +							    sizeof(sparse_banks[0]))))
> +					return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +			}
> +		}
>  	}
>  
>  	cpumask_clear(&hv_vcpu->tlb_flush);
> @@ -1890,6 +1920,41 @@ static u16 kvm_hvcall_signal_event(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *h
>  	return HV_STATUS_SUCCESS;
>  }
>  
> +static bool is_xmm_fast_hypercall(struct kvm_hv_hcall *hc)
> +{
> +	switch (hc->code) {
> +	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
> +	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
> +	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
> +	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
> +static inline void kvm_hv_hypercall_read_xmm(struct kvm_hv_hcall *hc)
> +{
> +	int reg;
> +
> +	kvm_fpu_get();
> +	for (reg = 0; reg < KVM_HV_HYPERCALL_MAX_XMM_REGISTERS; reg++)
> +		_kvm_read_sse_reg(reg, &hc->xmm[reg]);
> +	kvm_fpu_put();
> +	hc->xmm_dirty = false;
> +}
> +
> +static inline void kvm_hv_hypercall_write_xmm(struct kvm_hv_hcall *hc)
> +{
> +	int reg;
> +
> +	kvm_fpu_get();
> +	for (reg = 0; reg < KVM_HV_HYPERCALL_MAX_XMM_REGISTERS; reg++)
> +		_kvm_write_sse_reg(reg, &hc->xmm[reg]);
> +	kvm_fpu_put();
> +	hc->xmm_dirty = false;
> +}
> +
>  int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_hv_hcall hc;
> @@ -1926,6 +1991,9 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>  	hc.rep_idx = (hc.param >> HV_HYPERCALL_REP_START_OFFSET) & 0xfff;
>  	hc.rep = !!(hc.rep_cnt || hc.rep_idx);
>  
> +	if (is_xmm_fast_hypercall(&hc))
> +		kvm_hv_hypercall_read_xmm(&hc);

is_xmm_fast_hypercall() check should probably be complemented with " &&
hc.fast" as there's no point in reading this regs when the hypercall is
not 'fast'.

Also, we can probably defer kvm_hv_hypercall_read_xmm() until we know
how many regs we actually need to not read them all (we will always
need xmm[0] I guess so we can as well read it here).

> +
>  	trace_kvm_hv_hypercall(hc.code, hc.fast, hc.rep_cnt, hc.rep_idx,
>  			       hc.ingpa, hc.outgpa);
>  
> @@ -1961,28 +2029,28 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>  				kvm_hv_hypercall_complete_userspace;
>  		return 0;
>  	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
> -		if (unlikely(hc.fast || !hc.rep_cnt || hc.rep_idx)) {
> +		if (unlikely(!hc.rep_cnt || hc.rep_idx)) {
>  			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>  			break;
>  		}
>  		ret = kvm_hv_flush_tlb(vcpu, &hc, false);
>  		break;
>  	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
> -		if (unlikely(hc.fast || hc.rep)) {
> +		if (unlikely(hc.rep)) {
>  			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>  			break;
>  		}
>  		ret = kvm_hv_flush_tlb(vcpu, &hc, false);
>  		break;
>  	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
> -		if (unlikely(hc.fast || !hc.rep_cnt || hc.rep_idx)) {
> +		if (unlikely(!hc.rep_cnt || hc.rep_idx)) {
>  			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>  			break;
>  		}
>  		ret = kvm_hv_flush_tlb(vcpu, &hc, true);
>  		break;
>  	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
> -		if (unlikely(hc.fast || hc.rep)) {
> +		if (unlikely(hc.rep)) {
>  			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
>  			break;
>  		}
> @@ -2035,6 +2103,9 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>  		break;
>  	}
>  
> +	if (hc.xmm_dirty)
> +		kvm_hv_hypercall_write_xmm(&hc);
> +
>  	return kvm_hv_hypercall_complete(vcpu, ret);
>  }

-- 
Vitaly

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Vitaly Kuznetsov]

Siddharth Chandrasekaran <sidcha@amazon.de> writes:

> Now that all extant hypercalls that can use XMM registers (based on
> spec) for input/outputs are patched to support them, we can start
> advertising this feature to guests.
>
> Cc: Alexander Graf <graf@amazon.com>
> Cc: Evgeny Iakovlev <eyakovl@amazon.de>
> Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
> ---
>  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
>  arch/x86/kvm/hyperv.c              | 1 +
>  2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index e6cd3fee562b..1f160ef60509 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -49,10 +49,10 @@
>  /* Support for physical CPU dynamic partitioning events is available*/
>  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE	BIT(3)
>  /*
> - * Support for passing hypercall input parameter block via XMM
> + * Support for passing hypercall input and output parameter block via XMM
>   * registers is available
>   */
> -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE		BIT(4)
> +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE		BIT(4) | BIT(15)

TLFS 6.0b states that there are two distinct bits for input and output:

CPUID Leaf 0x40000003.EDX:
Bit 4: support for passing hypercall input via XMM registers is available.
Bit 15: support for returning hypercall output via XMM registers is available.

and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
anywhere, I'd suggest we just rename 

HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).

>  /* Support for a virtual guest idle state is available */
>  #define HV_X64_GUEST_IDLE_STATE_AVAILABLE		BIT(5)
>  /* Frequency MSRs available */
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index bf2f86f263f1..dd462c1d641d 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -2254,6 +2254,7 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
>  			ent->ebx |= HV_POST_MESSAGES;
>  			ent->ebx |= HV_SIGNAL_EVENTS;
>  
> +			ent->edx |= HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE;
>  			ent->edx |= HV_FEATURE_FREQUENCY_MSRS_AVAILABLE;
>  			ent->edx |= HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;

-- 
Vitaly

Re: [PATCH 3/4] KVM: x86: kvm_hv_flush_tlb use inputs from XMM registers

[Paolo Bonzini]

On 08/04/21 14:01, Vitaly Kuznetsov wrote:
> 
> Also, we can probably defer kvm_hv_hypercall_read_xmm() until we know
> how many regs we actually need to not read them all (we will always
> need xmm[0] I guess so we can as well read it here).

The cost is get/put FPU, so I think there's not much to gain from that.

Paolo

Re: [PATCH 3/4] KVM: x86: kvm_hv_flush_tlb use inputs from XMM registers

[Vitaly Kuznetsov]

Paolo Bonzini <pbonzini@redhat.com> writes:

> On 08/04/21 14:01, Vitaly Kuznetsov wrote:
>> 
>> Also, we can probably defer kvm_hv_hypercall_read_xmm() until we know
>> how many regs we actually need to not read them all (we will always
>> need xmm[0] I guess so we can as well read it here).
>
> The cost is get/put FPU, so I think there's not much to gain from that.
>

Maybe, I just think that in most cases we will only need xmm0. To make
the optimization work we can probably do kvm_get_fpu() once we figured
out that we're dealing with XMM hypercall and do kvm_put_fpu() when
we're done processing hypercall parameters. This way we don't need to do
get/put twice. We can certainly leave this idea to the (possible) future
optimizations.

-- 
Vitaly

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Siddharth Chandrasekaran]

On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote:
> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
>
> > Now that all extant hypercalls that can use XMM registers (based on
> > spec) for input/outputs are patched to support them, we can start
> > advertising this feature to guests.
> >
> > Cc: Alexander Graf <graf@amazon.com>
> > Cc: Evgeny Iakovlev <eyakovl@amazon.de>
> > Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
> > ---
> >  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
> >  arch/x86/kvm/hyperv.c              | 1 +
> >  2 files changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> > index e6cd3fee562b..1f160ef60509 100644
> > --- a/arch/x86/include/asm/hyperv-tlfs.h
> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> > @@ -49,10 +49,10 @@
> >  /* Support for physical CPU dynamic partitioning events is available*/
> >  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE    BIT(3)
> >  /*
> > - * Support for passing hypercall input parameter block via XMM
> > + * Support for passing hypercall input and output parameter block via XMM
> >   * registers is available
> >   */
> > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4)
> > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4) | BIT(15)
>
> TLFS 6.0b states that there are two distinct bits for input and output:
>
> CPUID Leaf 0x40000003.EDX:
> Bit 4: support for passing hypercall input via XMM registers is available.
> Bit 15: support for returning hypercall output via XMM registers is available.
>
> and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
> anywhere, I'd suggest we just rename
>
> HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
> and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).

That is how I had it initially; but then noticed that we would never
need to use either of them separately. So it seemed like a reasonable
abstraction to put them together.

~ Sid.



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

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Vitaly Kuznetsov]

Siddharth Chandrasekaran <sidcha@amazon.de> writes:

> On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote:
>> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
>>
>> > Now that all extant hypercalls that can use XMM registers (based on
>> > spec) for input/outputs are patched to support them, we can start
>> > advertising this feature to guests.
>> >
>> > Cc: Alexander Graf <graf@amazon.com>
>> > Cc: Evgeny Iakovlev <eyakovl@amazon.de>
>> > Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
>> > ---
>> >  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
>> >  arch/x86/kvm/hyperv.c              | 1 +
>> >  2 files changed, 3 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
>> > index e6cd3fee562b..1f160ef60509 100644
>> > --- a/arch/x86/include/asm/hyperv-tlfs.h
>> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
>> > @@ -49,10 +49,10 @@
>> >  /* Support for physical CPU dynamic partitioning events is available*/
>> >  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE    BIT(3)
>> >  /*
>> > - * Support for passing hypercall input parameter block via XMM
>> > + * Support for passing hypercall input and output parameter block via XMM
>> >   * registers is available
>> >   */
>> > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4)
>> > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4) | BIT(15)
>>
>> TLFS 6.0b states that there are two distinct bits for input and output:
>>
>> CPUID Leaf 0x40000003.EDX:
>> Bit 4: support for passing hypercall input via XMM registers is available.
>> Bit 15: support for returning hypercall output via XMM registers is available.
>>
>> and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
>> anywhere, I'd suggest we just rename
>>
>> HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
>> and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).
>
> That is how I had it initially; but then noticed that we would never
> need to use either of them separately. So it seemed like a reasonable
> abstraction to put them together.
>

Actually, we may. In theory, KVM userspace may decide to expose just
one of these two to the guest as it is not obliged to copy everything
from KVM_GET_SUPPORTED_HV_CPUID so we will need separate
guest_cpuid_has() checks.

(This reminds me of something I didn't see in your series:
we need to check that XMM hypercall parameters support was actually
exposed to the guest as it is illegal for a guest to use it otherwise --
and we will likely need two checks, for input and output).

Also, (and that's what triggered my comment) all other HV_ACCESS_* in
kvm_get_hv_cpuid() are single bits so my first impression was that you
forgot one bit, but then I saw that you combined them together.

-- 
Vitaly

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Wei Liu]

On Thu, Apr 08, 2021 at 04:20:54PM +0200, Siddharth Chandrasekaran wrote:
> On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote:
> > Siddharth Chandrasekaran <sidcha@amazon.de> writes:
> >
> > > Now that all extant hypercalls that can use XMM registers (based on
> > > spec) for input/outputs are patched to support them, we can start
> > > advertising this feature to guests.
> > >
> > > Cc: Alexander Graf <graf@amazon.com>
> > > Cc: Evgeny Iakovlev <eyakovl@amazon.de>
> > > Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
> > > ---
> > >  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
> > >  arch/x86/kvm/hyperv.c              | 1 +
> > >  2 files changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> > > index e6cd3fee562b..1f160ef60509 100644
> > > --- a/arch/x86/include/asm/hyperv-tlfs.h
> > > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> > > @@ -49,10 +49,10 @@
> > >  /* Support for physical CPU dynamic partitioning events is available*/
> > >  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE    BIT(3)
> > >  /*
> > > - * Support for passing hypercall input parameter block via XMM
> > > + * Support for passing hypercall input and output parameter block via XMM
> > >   * registers is available
> > >   */
> > > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4)
> > > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4) | BIT(15)
> >
> > TLFS 6.0b states that there are two distinct bits for input and output:
> >
> > CPUID Leaf 0x40000003.EDX:
> > Bit 4: support for passing hypercall input via XMM registers is available.
> > Bit 15: support for returning hypercall output via XMM registers is available.
> >
> > and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
> > anywhere, I'd suggest we just rename
> >
> > HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
> > and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).
> 
> That is how I had it initially; but then noticed that we would never
> need to use either of them separately. So it seemed like a reasonable
> abstraction to put them together.
> 

They are two separate things in TLFS. Please use two macros here.

Wei.

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Siddharth Chandrasekaran]

On Thu, Apr 08, 2021 at 04:44:23PM +0200, Vitaly Kuznetsov wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
>
>
>
> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
>
> > On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote:
> >> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
> >>
> >> > Now that all extant hypercalls that can use XMM registers (based on
> >> > spec) for input/outputs are patched to support them, we can start
> >> > advertising this feature to guests.
> >> >
> >> > Cc: Alexander Graf <graf@amazon.com>
> >> > Cc: Evgeny Iakovlev <eyakovl@amazon.de>
> >> > Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
> >> > ---
> >> >  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
> >> >  arch/x86/kvm/hyperv.c              | 1 +
> >> >  2 files changed, 3 insertions(+), 2 deletions(-)
> >> >
> >> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> >> > index e6cd3fee562b..1f160ef60509 100644
> >> > --- a/arch/x86/include/asm/hyperv-tlfs.h
> >> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> >> > @@ -49,10 +49,10 @@
> >> >  /* Support for physical CPU dynamic partitioning events is available*/
> >> >  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE    BIT(3)
> >> >  /*
> >> > - * Support for passing hypercall input parameter block via XMM
> >> > + * Support for passing hypercall input and output parameter block via XMM
> >> >   * registers is available
> >> >   */
> >> > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4)
> >> > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4) | BIT(15)
> >>
> >> TLFS 6.0b states that there are two distinct bits for input and output:
> >>
> >> CPUID Leaf 0x40000003.EDX:
> >> Bit 4: support for passing hypercall input via XMM registers is available.
> >> Bit 15: support for returning hypercall output via XMM registers is available.
> >>
> >> and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
> >> anywhere, I'd suggest we just rename
> >>
> >> HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
> >> and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).
> >
> > That is how I had it initially; but then noticed that we would never
> > need to use either of them separately. So it seemed like a reasonable
> > abstraction to put them together.
> >
>
> Actually, we may. In theory, KVM userspace may decide to expose just
> one of these two to the guest as it is not obliged to copy everything
> from KVM_GET_SUPPORTED_HV_CPUID so we will need separate
> guest_cpuid_has() checks.

Makes sense. I'll split them and add the checks.

> (This reminds me of something I didn't see in your series:
> we need to check that XMM hypercall parameters support was actually
> exposed to the guest as it is illegal for a guest to use it otherwise --
> and we will likely need two checks, for input and output).

We observed that Windows expects Hyper-V to support XMM params even if
we don't advertise this feature but if userspace wants to hide this
feature and the guest does it anyway, then it makes sense to treat it as
an illegal OP.

> Also, (and that's what triggered my comment) all other HV_ACCESS_* in
> kvm_get_hv_cpuid() are single bits so my first impression was that you
> forgot one bit, but then I saw that you combined them together.

~ Sid.



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

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Siddharth Chandrasekaran]

On Thu, Apr 08, 2021 at 03:44:46PM +0000, Wei Liu wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
>
>
>
> On Thu, Apr 08, 2021 at 04:20:54PM +0200, Siddharth Chandrasekaran wrote:
> > On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote:
> > > Siddharth Chandrasekaran <sidcha@amazon.de> writes:
> > >
> > > > Now that all extant hypercalls that can use XMM registers (based on
> > > > spec) for input/outputs are patched to support them, we can start
> > > > advertising this feature to guests.
> > > >
> > > > Cc: Alexander Graf <graf@amazon.com>
> > > > Cc: Evgeny Iakovlev <eyakovl@amazon.de>
> > > > Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
> > > > ---
> > > >  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
> > > >  arch/x86/kvm/hyperv.c              | 1 +
> > > >  2 files changed, 3 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> > > > index e6cd3fee562b..1f160ef60509 100644
> > > > --- a/arch/x86/include/asm/hyperv-tlfs.h
> > > > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> > > > @@ -49,10 +49,10 @@
> > > >  /* Support for physical CPU dynamic partitioning events is available*/
> > > >  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE    BIT(3)
> > > >  /*
> > > > - * Support for passing hypercall input parameter block via XMM
> > > > + * Support for passing hypercall input and output parameter block via XMM
> > > >   * registers is available
> > > >   */
> > > > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4)
> > > > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4) | BIT(15)
> > >
> > > TLFS 6.0b states that there are two distinct bits for input and output:
> > >
> > > CPUID Leaf 0x40000003.EDX:
> > > Bit 4: support for passing hypercall input via XMM registers is available.
> > > Bit 15: support for returning hypercall output via XMM registers is available.
> > >
> > > and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
> > > anywhere, I'd suggest we just rename
> > >
> > > HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
> > > and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).
> >
> > That is how I had it initially; but then noticed that we would never
> > need to use either of them separately. So it seemed like a reasonable
> > abstraction to put them together.
> >
>
> They are two separate things in TLFS. Please use two macros here.

Ack, will split them.

~ Sid.



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

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Vitaly Kuznetsov]

Siddharth Chandrasekaran <sidcha@amazon.de> writes:

> On Thu, Apr 08, 2021 at 04:44:23PM +0200, Vitaly Kuznetsov wrote:
>> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
>>
>>
>>
>> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
>>
>> > On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote:
>> >> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
>> >>
>> >> > Now that all extant hypercalls that can use XMM registers (based on
>> >> > spec) for input/outputs are patched to support them, we can start
>> >> > advertising this feature to guests.
>> >> >
>> >> > Cc: Alexander Graf <graf@amazon.com>
>> >> > Cc: Evgeny Iakovlev <eyakovl@amazon.de>
>> >> > Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
>> >> > ---
>> >> >  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
>> >> >  arch/x86/kvm/hyperv.c              | 1 +
>> >> >  2 files changed, 3 insertions(+), 2 deletions(-)
>> >> >
>> >> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
>> >> > index e6cd3fee562b..1f160ef60509 100644
>> >> > --- a/arch/x86/include/asm/hyperv-tlfs.h
>> >> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
>> >> > @@ -49,10 +49,10 @@
>> >> >  /* Support for physical CPU dynamic partitioning events is available*/
>> >> >  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE    BIT(3)
>> >> >  /*
>> >> > - * Support for passing hypercall input parameter block via XMM
>> >> > + * Support for passing hypercall input and output parameter block via XMM
>> >> >   * registers is available
>> >> >   */
>> >> > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4)
>> >> > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4) | BIT(15)
>> >>
>> >> TLFS 6.0b states that there are two distinct bits for input and output:
>> >>
>> >> CPUID Leaf 0x40000003.EDX:
>> >> Bit 4: support for passing hypercall input via XMM registers is available.
>> >> Bit 15: support for returning hypercall output via XMM registers is available.
>> >>
>> >> and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
>> >> anywhere, I'd suggest we just rename
>> >>
>> >> HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
>> >> and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).
>> >
>> > That is how I had it initially; but then noticed that we would never
>> > need to use either of them separately. So it seemed like a reasonable
>> > abstraction to put them together.
>> >
>>
>> Actually, we may. In theory, KVM userspace may decide to expose just
>> one of these two to the guest as it is not obliged to copy everything
>> from KVM_GET_SUPPORTED_HV_CPUID so we will need separate
>> guest_cpuid_has() checks.
>
> Makes sense. I'll split them and add the checks.
>
>> (This reminds me of something I didn't see in your series:
>> we need to check that XMM hypercall parameters support was actually
>> exposed to the guest as it is illegal for a guest to use it otherwise --
>> and we will likely need two checks, for input and output).
>
> We observed that Windows expects Hyper-V to support XMM params even if
> we don't advertise this feature but if userspace wants to hide this
> feature and the guest does it anyway, then it makes sense to treat it as
> an illegal OP.
>

Out of pure curiosity, which Windows version behaves like that? And how
does this work with KVM without your patches?

Sane KVM userspaces will certainly expose both XMM input and output
capabilities together but having an ability to hide one or both of them
may come handy while debugging.

Also, we weren't enforcing the rule that enlightenments not exposed to
the guest don't work, even the whole Hyper-V emulation interface was
available to all guests who were smart enough to know how to enable it!
I don't like this for two reasons: security (large attack surface) and
the fact that someone 'smart' may decide to use Hyper-V emulation
features on KVM as 'general purpose' features saying 'they're always
available anyway', this risks becoming an ABI.

Let's at least properly check if the feature was exposed to the guest
for all new enlightenments.

-- 
Vitaly

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Siddharth Chandrasekaran]

On Fri, Apr 09, 2021 at 09:38:03AM +0200, Vitaly Kuznetsov wrote:
> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
> > On Thu, Apr 08, 2021 at 04:44:23PM +0200, Vitaly Kuznetsov wrote:
> >> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
> >> > On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote:
> >> >> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
> >> >>
> >> >> > Now that all extant hypercalls that can use XMM registers (based on
> >> >> > spec) for input/outputs are patched to support them, we can start
> >> >> > advertising this feature to guests.
> >> >> >
> >> >> > Cc: Alexander Graf <graf@amazon.com>
> >> >> > Cc: Evgeny Iakovlev <eyakovl@amazon.de>
> >> >> > Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
> >> >> > ---
> >> >> >  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
> >> >> >  arch/x86/kvm/hyperv.c              | 1 +
> >> >> >  2 files changed, 3 insertions(+), 2 deletions(-)
> >> >> >
> >> >> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> >> >> > index e6cd3fee562b..1f160ef60509 100644
> >> >> > --- a/arch/x86/include/asm/hyperv-tlfs.h
> >> >> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> >> >> > @@ -49,10 +49,10 @@
> >> >> >  /* Support for physical CPU dynamic partitioning events is available*/
> >> >> >  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE    BIT(3)
> >> >> >  /*
> >> >> > - * Support for passing hypercall input parameter block via XMM
> >> >> > + * Support for passing hypercall input and output parameter block via XMM
> >> >> >   * registers is available
> >> >> >   */
> >> >> > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4)
> >> >> > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4) | BIT(15)
> >> >>
> >> >> TLFS 6.0b states that there are two distinct bits for input and output:
> >> >>
> >> >> CPUID Leaf 0x40000003.EDX:
> >> >> Bit 4: support for passing hypercall input via XMM registers is available.
> >> >> Bit 15: support for returning hypercall output via XMM registers is available.
> >> >>
> >> >> and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
> >> >> anywhere, I'd suggest we just rename
> >> >>
> >> >> HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
> >> >> and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).
> >> >
> >> > That is how I had it initially; but then noticed that we would never
> >> > need to use either of them separately. So it seemed like a reasonable
> >> > abstraction to put them together.
> >> >
> >>
> >> Actually, we may. In theory, KVM userspace may decide to expose just
> >> one of these two to the guest as it is not obliged to copy everything
> >> from KVM_GET_SUPPORTED_HV_CPUID so we will need separate
> >> guest_cpuid_has() checks.
> >
> > Makes sense. I'll split them and add the checks.
> >
> >> (This reminds me of something I didn't see in your series:
> >> we need to check that XMM hypercall parameters support was actually
> >> exposed to the guest as it is illegal for a guest to use it otherwise --
> >> and we will likely need two checks, for input and output).
> >
> > We observed that Windows expects Hyper-V to support XMM params even if
> > we don't advertise this feature but if userspace wants to hide this
> > feature and the guest does it anyway, then it makes sense to treat it as
> > an illegal OP.
> >
> 
> Out of pure curiosity, which Windows version behaves like that? And how
> does this work with KVM without your patches?

The guest is a Windows Server 2016 on which we are trying to enable VBS
and handle it through the VSM API. When VBS is enabled on the guest, it
starts using many other (new) hypercalls and some of them don't honor
the CPUID bits (4, 15) that indicate the presence of XMM params support.

> Sane KVM userspaces will certainly expose both XMM input and output
> capabilities together but having an ability to hide one or both of them
> may come handy while debugging.
> 
> Also, we weren't enforcing the rule that enlightenments not exposed to
> the guest don't work, even the whole Hyper-V emulation interface was
> available to all guests who were smart enough to know how to enable it!
> I don't like this for two reasons: security (large attack surface) and
> the fact that someone 'smart' may decide to use Hyper-V emulation
> features on KVM as 'general purpose' features saying 'they're always
> available anyway', this risks becoming an ABI.
> 
> Let's at least properly check if the feature was exposed to the guest
> for all new enlightenments.

Agreed.

~ Sid.



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

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Siddharth Chandrasekaran]

On Thu, Apr 08, 2021 at 04:44:23PM +0200, Vitaly Kuznetsov wrote:
> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
> > On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote:
> >> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
> >> > Now that all extant hypercalls that can use XMM registers (based on
> >> > spec) for input/outputs are patched to support them, we can start
> >> > advertising this feature to guests.
> >> >
> >> > Cc: Alexander Graf <graf@amazon.com>
> >> > Cc: Evgeny Iakovlev <eyakovl@amazon.de>
> >> > Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
> >> > ---
> >> >  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
> >> >  arch/x86/kvm/hyperv.c              | 1 +
> >> >  2 files changed, 3 insertions(+), 2 deletions(-)
> >> >
> >> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> >> > index e6cd3fee562b..1f160ef60509 100644
> >> > --- a/arch/x86/include/asm/hyperv-tlfs.h
> >> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> >> > @@ -49,10 +49,10 @@
> >> >  /* Support for physical CPU dynamic partitioning events is available*/
> >> >  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE    BIT(3)
> >> >  /*
> >> > - * Support for passing hypercall input parameter block via XMM
> >> > + * Support for passing hypercall input and output parameter block via XMM
> >> >   * registers is available
> >> >   */
> >> > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4)
> >> > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4) | BIT(15)
> >>
> >> TLFS 6.0b states that there are two distinct bits for input and output:
> >>
> >> CPUID Leaf 0x40000003.EDX:
> >> Bit 4: support for passing hypercall input via XMM registers is available.
> >> Bit 15: support for returning hypercall output via XMM registers is available.
> >>
> >> and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
> >> anywhere, I'd suggest we just rename
> >>
> >> HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
> >> and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).
> >
> > That is how I had it initially; but then noticed that we would never
> > need to use either of them separately. So it seemed like a reasonable
> > abstraction to put them together.
> >
> 
> Actually, we may. In theory, KVM userspace may decide to expose just
> one of these two to the guest as it is not obliged to copy everything
> from KVM_GET_SUPPORTED_HV_CPUID so we will need separate
> guest_cpuid_has() checks.

Looks like guest_cpuid_has() check is for x86 CPU features only (if I'm
not mistaken) and I don't see a suitable alternative that looks into
vcpu->arch.cpuid_entries[]. So I plan to add a new method
hv_guest_cpuid_has() in hyperv.c to have this check; does that sound
right to you?

If you can give a quick go-ahead, I'll make the changes requested so
far and send v2 this series.

Thanks.

~ Sid.



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

Re: [PATCH 4/4] KVM: hyper-v: Advertise support for fast XMM hypercalls

[Vitaly Kuznetsov]

Siddharth Chandrasekaran <sidcha@amazon.de> writes:

> On Thu, Apr 08, 2021 at 04:44:23PM +0200, Vitaly Kuznetsov wrote:
>> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
>> > On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote:
>> >> Siddharth Chandrasekaran <sidcha@amazon.de> writes:
>> >> > Now that all extant hypercalls that can use XMM registers (based on
>> >> > spec) for input/outputs are patched to support them, we can start
>> >> > advertising this feature to guests.
>> >> >
>> >> > Cc: Alexander Graf <graf@amazon.com>
>> >> > Cc: Evgeny Iakovlev <eyakovl@amazon.de>
>> >> > Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
>> >> > ---
>> >> >  arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
>> >> >  arch/x86/kvm/hyperv.c              | 1 +
>> >> >  2 files changed, 3 insertions(+), 2 deletions(-)
>> >> >
>> >> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
>> >> > index e6cd3fee562b..1f160ef60509 100644
>> >> > --- a/arch/x86/include/asm/hyperv-tlfs.h
>> >> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
>> >> > @@ -49,10 +49,10 @@
>> >> >  /* Support for physical CPU dynamic partitioning events is available*/
>> >> >  #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE    BIT(3)
>> >> >  /*
>> >> > - * Support for passing hypercall input parameter block via XMM
>> >> > + * Support for passing hypercall input and output parameter block via XMM
>> >> >   * registers is available
>> >> >   */
>> >> > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4)
>> >> > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE                BIT(4) | BIT(15)
>> >>
>> >> TLFS 6.0b states that there are two distinct bits for input and output:
>> >>
>> >> CPUID Leaf 0x40000003.EDX:
>> >> Bit 4: support for passing hypercall input via XMM registers is available.
>> >> Bit 15: support for returning hypercall output via XMM registers is available.
>> >>
>> >> and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used
>> >> anywhere, I'd suggest we just rename
>> >>
>> >> HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE
>> >> and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15).
>> >
>> > That is how I had it initially; but then noticed that we would never
>> > need to use either of them separately. So it seemed like a reasonable
>> > abstraction to put them together.
>> >
>> 
>> Actually, we may. In theory, KVM userspace may decide to expose just
>> one of these two to the guest as it is not obliged to copy everything
>> from KVM_GET_SUPPORTED_HV_CPUID so we will need separate
>> guest_cpuid_has() checks.
>
> Looks like guest_cpuid_has() check is for x86 CPU features only (if I'm
> not mistaken) and I don't see a suitable alternative that looks into
> vcpu->arch.cpuid_entries[]. So I plan to add a new method
> hv_guest_cpuid_has() in hyperv.c to have this check; does that sound
> right to you?
> If you can give a quick go-ahead, I'll make the changes requested so
> far and send v2 this series.

Sorry my mistake, guest_cpuid_has() was the wrong function to name. In the
meantime I started working on fine-grained access to the existing
Hyper-V enlightenments as well and I think the best approach would be to
cache CPUID 0x40000003 (EAX, EBX, EDX) in kvm_hv_set_cpuid()  to avoid
looping through all guest CPUID entries on every hypercall. Your check
will then look like

 if (hv_vcpu->cpuid_cache.features_edx & HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE)
 ...


 if (hv_vcpu->cpuid_cache.features_edx & HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE)
 ...

We can wrap this into a hv_guest_cpuid_has() helper indeed, it'll look like:

 if (hv_guest_cpuid_has(vcpu, HYPERV_CPUID_FEATURES, CPUID_EDX, HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE))
 ...

but I'm not sure it's worth it, maybe raw check is shorter and better.

I plan to send something out in a day or two, I'll Cc: you. Feel free to
do v2 without this, if your series gets merged first I can just add the
'fine-grained access' to mine.

Thanks!

-- 
Vitaly