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Message-Id: <20210913200132.3396598-5-sohil.mehta@intel.com>
Date: Mon, 13 Sep 2021 13:01:23 -0700
From: Sohil Mehta <sohil.mehta@...el.com>
To: x86@...nel.org
Cc: Sohil Mehta <sohil.mehta@...el.com>,
Tony Luck <tony.luck@...el.com>,
Dave Hansen <dave.hansen@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"H . Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...nel.org>,
Jens Axboe <axboe@...nel.dk>,
Christian Brauner <christian@...uner.io>,
Peter Zijlstra <peterz@...radead.org>,
Shuah Khan <shuah@...nel.org>, Arnd Bergmann <arnd@...db.de>,
Jonathan Corbet <corbet@....net>,
Ashok Raj <ashok.raj@...el.com>,
Jacob Pan <jacob.jun.pan@...ux.intel.com>,
Gayatri Kammela <gayatri.kammela@...el.com>,
Zeng Guang <guang.zeng@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
Randy E Witt <randy.e.witt@...el.com>,
Ravi V Shankar <ravi.v.shankar@...el.com>,
Ramesh Thomas <ramesh.thomas@...el.com>,
linux-api@...r.kernel.org, linux-arch@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: [RFC PATCH 04/13] x86/fpu/xstate: Enumerate User Interrupts supervisor state
Enable xstate supervisor support for User Interrupts by default.
The user interrupt state for a task consists of the MSR state and the
User Interrupt Flag (UIF) value. XSAVES and XRSTORS handle saving and
restoring both of these states.
<The supervisor XSTATE code might be reworked based on issues reported
in the past. The Uintr context switching code would also need rework and
additional testing in that regard.>
Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
---
arch/x86/include/asm/fpu/types.h | 20 +++++++++++++++++++-
arch/x86/include/asm/fpu/xstate.h | 3 ++-
arch/x86/kernel/cpu/common.c | 6 ++++++
arch/x86/kernel/fpu/xstate.c | 20 +++++++++++++++++---
4 files changed, 44 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index f5a38a5f3ae1..b614f1416bea 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -118,7 +118,7 @@ enum xfeature {
XFEATURE_RSRVD_COMP_11,
XFEATURE_RSRVD_COMP_12,
XFEATURE_RSRVD_COMP_13,
- XFEATURE_RSRVD_COMP_14,
+ XFEATURE_UINTR,
XFEATURE_LBR,
XFEATURE_MAX,
@@ -135,6 +135,7 @@ enum xfeature {
#define XFEATURE_MASK_PT (1 << XFEATURE_PT_UNIMPLEMENTED_SO_FAR)
#define XFEATURE_MASK_PKRU (1 << XFEATURE_PKRU)
#define XFEATURE_MASK_PASID (1 << XFEATURE_PASID)
+#define XFEATURE_MASK_UINTR (1 << XFEATURE_UINTR)
#define XFEATURE_MASK_LBR (1 << XFEATURE_LBR)
#define XFEATURE_MASK_FPSSE (XFEATURE_MASK_FP | XFEATURE_MASK_SSE)
@@ -237,6 +238,23 @@ struct pkru_state {
u32 pad;
} __packed;
+/*
+ * State component 14 is supervisor state used for User Interrupts state.
+ * The size of this state is 48 bytes
+ */
+struct uintr_state {
+ u64 handler;
+ u64 stack_adjust;
+ u32 uitt_size;
+ u8 uinv;
+ u8 pad1;
+ u8 pad2;
+ u8 uif_pad3; /* bit 7 - UIF, bits 6:0 - reserved */
+ u64 upid_addr;
+ u64 uirr;
+ u64 uitt_addr;
+} __packed;
+
/*
* State component 15: Architectural LBR configuration state.
* The size of Arch LBR state depends on the number of LBRs (lbr_depth).
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 109dfcc75299..4dd4e83c0c9d 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -44,7 +44,8 @@
(XFEATURE_MASK_USER_SUPPORTED & ~XFEATURE_MASK_PKRU)
/* All currently supported supervisor features */
-#define XFEATURE_MASK_SUPERVISOR_SUPPORTED (XFEATURE_MASK_PASID)
+#define XFEATURE_MASK_SUPERVISOR_SUPPORTED (XFEATURE_MASK_PASID | \
+ XFEATURE_MASK_UINTR)
/*
* A supervisor state component may not always contain valuable information,
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 55fee930b6d1..3a0a3f5cfe0f 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -334,6 +334,12 @@ static __always_inline void setup_uintr(struct cpuinfo_x86 *c)
if (!cpu_has(c, X86_FEATURE_UINTR))
goto disable_uintr;
+ /* Confirm XSAVE support for UINTR is present. */
+ if (!cpu_has_xfeatures(XFEATURE_MASK_UINTR, NULL)) {
+ pr_info_once("x86: User Interrupts (UINTR) not enabled. XSAVE support for UINTR is missing.\n");
+ goto clear_uintr_cap;
+ }
+
/*
* User Interrupts currently doesn't support PTI. For processors that
* support User interrupts PTI in auto mode will default to off. Need
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c8def1b7f8fb..ab19403effb0 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -38,6 +38,10 @@ static const char *xfeature_names[] =
"Processor Trace (unused)" ,
"Protection Keys User registers",
"PASID state",
+ "unknown xstate feature 11",
+ "unknown xstate feature 12",
+ "unknown xstate feature 13",
+ "User Interrupts registers",
"unknown xstate feature" ,
};
@@ -53,6 +57,10 @@ static short xsave_cpuid_features[] __initdata = {
X86_FEATURE_INTEL_PT,
X86_FEATURE_PKU,
X86_FEATURE_ENQCMD,
+ -1, /* Unknown 11 */
+ -1, /* Unknown 12 */
+ -1, /* Unknown 13 */
+ X86_FEATURE_UINTR,
};
/*
@@ -236,6 +244,7 @@ static void __init print_xstate_features(void)
print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
print_xstate_feature(XFEATURE_MASK_PKRU);
print_xstate_feature(XFEATURE_MASK_PASID);
+ print_xstate_feature(XFEATURE_MASK_UINTR);
}
/*
@@ -372,7 +381,8 @@ static void __init print_xstate_offset_size(void)
XFEATURE_MASK_PKRU | \
XFEATURE_MASK_BNDREGS | \
XFEATURE_MASK_BNDCSR | \
- XFEATURE_MASK_PASID)
+ XFEATURE_MASK_PASID | \
+ XFEATURE_MASK_UINTR)
/*
* setup the xstate image representing the init state
@@ -532,6 +542,7 @@ static void check_xstate_against_struct(int nr)
XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM, struct avx_512_hi16_state);
XCHECK_SZ(sz, nr, XFEATURE_PKRU, struct pkru_state);
XCHECK_SZ(sz, nr, XFEATURE_PASID, struct ia32_pasid_state);
+ XCHECK_SZ(sz, nr, XFEATURE_UINTR, struct uintr_state);
/*
* Make *SURE* to add any feature numbers in below if
@@ -539,9 +550,12 @@ static void check_xstate_against_struct(int nr)
* numbers.
*/
if ((nr < XFEATURE_YMM) ||
- (nr >= XFEATURE_MAX) ||
(nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) ||
- ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_LBR))) {
+ (nr == XFEATURE_RSRVD_COMP_11) ||
+ (nr == XFEATURE_RSRVD_COMP_12) ||
+ (nr == XFEATURE_RSRVD_COMP_13) ||
+ (nr == XFEATURE_LBR) ||
+ (nr >= XFEATURE_MAX)) {
WARN_ONCE(1, "no structure for xstate: %d\n", nr);
XSTATE_WARN_ON(1);
}
--
2.33.0
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