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 general purpose registers.
The XMM fast hypercall interface uses an additional six XMM registers
(XMM0 to XMM5) to allow the caller 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.
Although the Hyper-v TLFS mentions that a guest cannot use this feature
unless the hypervisor advertises support for it, some hypercalls which
we plan on upstreaming in future uses them anyway. This patchset adds
necessary infrastructure for handling input/output via XMM registers and
patches kvm_hv_flush_tlb() to use xmm input arguments.
~ Sid.
v3 -> v4:
- Rebase to latest master
- Remove unused loop variable j
v2 -> v3:
- Remove inline for kvm_hv_hypercall_{read,write}_xmm()
- Fix typo: s/ouput/output/
- Remove sse128_t from kvm_emulate.h
- Reword comment to match TLFS wording
- Move num XMM registers macro to hyperv-tlfs.h
- Stop advertising HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE
v1 -> v2:
- Add hc.fast to is_xmm_fast_hypercall() check
- Split CPUID feature bits for input and output
Siddharth Chandrasekaran (4):
KVM: x86: Move FPU register accessors into fpu.h
KVM: hyper-v: Collect hypercall params into struct
KVM: x86: kvm_hv_flush_tlb use inputs from XMM registers
KVM: hyper-v: Advertise support for fast XMM hypercalls
arch/x86/include/asm/hyperv-tlfs.h | 10 +-
arch/x86/kvm/emulate.c | 137 +++---------------
arch/x86/kvm/fpu.h | 140 ++++++++++++++++++
arch/x86/kvm/hyperv.c | 222 +++++++++++++++++++----------
arch/x86/kvm/kvm_emulate.h | 3 +-
5 files changed, 310 insertions(+), 202 deletions(-)
create mode 100644 arch/x86/kvm/fpu.h
--
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
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 <[email protected]>
Cc: Evgeny Iakovlev <[email protected]>
Signed-off-by: Siddharth Chandrasekaran <[email protected]>
---
arch/x86/kvm/emulate.c | 137 +++++-------------------------------
arch/x86/kvm/fpu.h | 140 +++++++++++++++++++++++++++++++++++++
arch/x86/kvm/kvm_emulate.h | 3 +-
3 files changed, 158 insertions(+), 122 deletions(-)
create mode 100644 arch/x86/kvm/fpu.h
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8a0ccdb56076..493511efa3dc 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>
@@ -1081,116 +1080,14 @@ 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 +1098,9 @@ 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 +1114,9 @@ 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 +1135,7 @@ 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 +1186,7 @@ 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 +1763,10 @@ 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 +4021,11 @@ 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 +4069,7 @@ 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 +4086,7 @@ 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;
}
@@ -5436,9 +5333,9 @@ 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);
@@ -5449,7 +5346,7 @@ 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
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index f016838faedd..798508e8b6f5 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -13,6 +13,7 @@
#define _ASM_X86_KVM_X86_EMULATE_H
#include <asm/desc_defs.h>
+#include "fpu.h"
struct x86_emulate_ctxt;
enum x86_intercept;
@@ -236,8 +237,6 @@ struct x86_emulate_ops {
int (*set_xcr)(struct x86_emulate_ctxt *ctxt, u32 index, u64 xcr);
};
-typedef u32 __attribute__((vector_size(16))) sse128_t;
-
/* Type, address-of, and value of an instruction's operand. */
struct operand {
enum { OP_REG, OP_MEM, OP_MEM_STR, OP_IMM, OP_XMM, OP_MM, OP_NONE } type;
--
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
On Wed, May 26, 2021 at 10:56:07AM +0200, Siddharth Chandrasekaran wrote:
> 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 general purpose registers.
>
> The XMM fast hypercall interface uses an additional six XMM registers
> (XMM0 to XMM5) to allow the caller 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.
>
> Although the Hyper-v TLFS mentions that a guest cannot use this feature
> unless the hypervisor advertises support for it, some hypercalls which
> we plan on upstreaming in future uses them anyway. This patchset adds
> necessary infrastructure for handling input/output via XMM registers and
> patches kvm_hv_flush_tlb() to use xmm input arguments.
Hi Paolo,
Are you expecting more reviews on these patches?
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
On 30/06/21 13:56, Siddharth Chandrasekaran wrote:
> On Wed, May 26, 2021 at 10:56:07AM +0200, Siddharth Chandrasekaran wrote:
>> 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 general purpose registers.
>>
>> The XMM fast hypercall interface uses an additional six XMM registers
>> (XMM0 to XMM5) to allow the caller 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.
>>
>> Although the Hyper-v TLFS mentions that a guest cannot use this feature
>> unless the hypervisor advertises support for it, some hypercalls which
>> we plan on upstreaming in future uses them anyway. This patchset adds
>> necessary infrastructure for handling input/output via XMM registers and
>> patches kvm_hv_flush_tlb() to use xmm input arguments.
>
> Hi Paolo,
>
> Are you expecting more reviews on these patches?
They are part of 5.14 already. :)
Paolo
On Tue, Jul 06, 2021 at 05:04:59PM +0200, Paolo Bonzini wrote:
> On 30/06/21 13:56, Siddharth Chandrasekaran wrote:
> > On Wed, May 26, 2021 at 10:56:07AM +0200, Siddharth Chandrasekaran wrote:
> > > 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 general purpose registers.
> > >
> > > The XMM fast hypercall interface uses an additional six XMM registers
> > > (XMM0 to XMM5) to allow the caller 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.
> > >
> > > Although the Hyper-v TLFS mentions that a guest cannot use this feature
> > > unless the hypervisor advertises support for it, some hypercalls which
> > > we plan on upstreaming in future uses them anyway. This patchset adds
> > > necessary infrastructure for handling input/output via XMM registers and
> > > patches kvm_hv_flush_tlb() to use xmm input arguments.
> >
> > Hi Paolo,
> >
> > Are you expecting more reviews on these patches?
>
> They are part of 5.14 already. :)
Ahh, I see them now. I was expecting them to show up in master - that was
the confusion.
Thanks! :)
~ Sid
Amazon Development Center Germany GmbH
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Sitz: Berlin
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On 06/07/21 17:15, Siddharth Chandrasekaran wrote:
> On Tue, Jul 06, 2021 at 05:04:59PM +0200, Paolo Bonzini wrote:
>> On 30/06/21 13:56, Siddharth Chandrasekaran wrote:
>>> On Wed, May 26, 2021 at 10:56:07AM +0200, Siddharth Chandrasekaran wrote:
>>>> 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 general purpose registers.
>>>>
>>>> The XMM fast hypercall interface uses an additional six XMM registers
>>>> (XMM0 to XMM5) to allow the caller 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.
>>>>
>>>> Although the Hyper-v TLFS mentions that a guest cannot use this feature
>>>> unless the hypervisor advertises support for it, some hypercalls which
>>>> we plan on upstreaming in future uses them anyway. This patchset adds
>>>> necessary infrastructure for handling input/output via XMM registers and
>>>> patches kvm_hv_flush_tlb() to use xmm input arguments.
>>>
>>> Hi Paolo,
>>>
>>> Are you expecting more reviews on these patches?
>>
>> They are part of 5.14 already. :)
>
> Ahh, I see them now. I was expecting them to show up in master - that was
> the confusion.
No problem! The patches for the rc period (in your case it was 5.13) go
in master, while yours ended up in next (destined for 5.14).
I usually update master only after 5.14-rc1 is out. In this case I
didn't even have access to kvm.git on the day that Linus pulled your
patches into his tree.
Paolo