From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
get_xsave_addr() sounds like it works on generic XSAVE buffers. It
does not. It only works on kernel XSAVE buffers which are part of the
FPU fpstate.
Give it a better name: get_fpstate_addr(). Also add warnings to it in
case non-fpstate features are requested (NULL should be returned for
these, but WARN() anyway).
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
---
b/arch/x86/include/asm/fpu/xstate.h | 2 +-
b/arch/x86/kernel/fpu/xstate.c | 11 ++++++-----
b/arch/x86/kvm/x86.c | 8 ++++----
3 files changed, 11 insertions(+), 10 deletions(-)
diff -puN arch/x86/include/asm/fpu/xstate.h~get_xsave_addr-warning arch/x86/include/asm/fpu/xstate.h
--- a/arch/x86/include/asm/fpu/xstate.h~get_xsave_addr-warning 2021-06-22 14:49:11.268051751 -0700
+++ b/arch/x86/include/asm/fpu/xstate.h 2021-06-22 14:49:11.279051751 -0700
@@ -134,7 +134,7 @@ extern u64 xstate_fx_sw_bytes[USER_XSTAT
extern void __init update_regset_xstate_info(unsigned int size,
u64 xstate_mask);
-void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
+void *get_fpstate_addr(struct xregs_state *xsave, int xfeature_nr);
int xfeature_size(int xfeature_nr);
int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf);
int copy_sigframe_from_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf);
diff -puN arch/x86/kernel/fpu/xstate.c~get_xsave_addr-warning arch/x86/kernel/fpu/xstate.c
--- a/arch/x86/kernel/fpu/xstate.c~get_xsave_addr-warning 2021-06-22 14:49:11.270051751 -0700
+++ b/arch/x86/kernel/fpu/xstate.c 2021-06-22 14:49:11.279051751 -0700
@@ -878,7 +878,8 @@ static void *__raw_xsave_addr(struct xre
}
/*
* Given the xsave area and a state inside, this function returns the
- * address of the state.
+ * address of the state. This only works on kernel fpstate, not on
+ * generic buffers created with XSAVE*.
*
* This is the API that is called to get xstate address in either
* standard format or compacted format of xsave area.
@@ -894,7 +895,7 @@ static void *__raw_xsave_addr(struct xre
* address of the state in the xsave area, or NULL if the
* field is not present in the xsave buffer.
*/
-void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
+void *get_fpstate_addr(struct xregs_state *xsave, int xfeature_nr)
{
/*
* Do we even *have* xsave state?
@@ -906,8 +907,8 @@ void *get_xsave_addr(struct xregs_state
* We should not ever be requesting features that we
* have not enabled.
*/
- WARN_ONCE(!(xfeatures_mask_all & BIT_ULL(xfeature_nr)),
- "get of unsupported state");
+ WARN_ONCE(!(xfeatures_mask_fpstate() & BIT_ULL(xfeature_nr)),
+ "get of unsupported fpstate");
/*
* This assumes the last 'xsave*' instruction to
* have requested that 'xfeature_nr' be saved.
@@ -924,7 +925,7 @@ void *get_xsave_addr(struct xregs_state
return __raw_xsave_addr(xsave, xfeature_nr);
}
-EXPORT_SYMBOL_GPL(get_xsave_addr);
+EXPORT_SYMBOL_GPL(get_fpstate_addr);
#ifdef CONFIG_ARCH_HAS_PKEYS
diff -puN arch/x86/kvm/x86.c~get_xsave_addr-warning arch/x86/kvm/x86.c
--- a/arch/x86/kvm/x86.c~get_xsave_addr-warning 2021-06-22 14:49:11.274051751 -0700
+++ b/arch/x86/kvm/x86.c 2021-06-22 14:49:11.284051751 -0700
@@ -4602,7 +4602,7 @@ static void fill_xsave(u8 *dest, struct
memcpy(dest + offset, &vcpu->arch.pkru,
sizeof(vcpu->arch.pkru));
} else {
- src = get_xsave_addr(xsave, xfeature_nr);
+ src = get_fpstate_addr(xsave, xfeature_nr);
if (src)
memcpy(dest + offset, src, size);
}
@@ -4645,7 +4645,7 @@ static void load_xsave(struct kvm_vcpu *
memcpy(&vcpu->arch.pkru, src + offset,
sizeof(vcpu->arch.pkru));
} else {
- void *dest = get_xsave_addr(xsave, xfeature_nr);
+ void *dest = get_fpstate_addr(xsave, xfeature_nr);
if (dest)
memcpy(dest, src + offset, size);
@@ -10479,11 +10479,11 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcp
*/
if (init_event)
kvm_put_guest_fpu(vcpu);
- mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu->state.xsave,
+ mpx_state_buffer = get_fpstate_addr(&vcpu->arch.guest_fpu->state.xsave,
XFEATURE_BNDREGS);
if (mpx_state_buffer)
memset(mpx_state_buffer, 0, sizeof(struct mpx_bndreg_state));
- mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu->state.xsave,
+ mpx_state_buffer = get_fpstate_addr(&vcpu->arch.guest_fpu->state.xsave,
XFEATURE_BNDCSR);
if (mpx_state_buffer)
memset(mpx_state_buffer, 0, sizeof(struct mpx_bndcsr));
_
