[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240521073505.2190633-1-kirill.shutemov@linux.intel.com>
Date: Tue, 21 May 2024 10:35:05 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>
Cc: linux-coco@...ts.linux.dev,
linux-kernel@...r.kernel.org,
cho@...rosoft.com,
decui@...rosoft.com,
John.Starks@...rosoft.com
Subject: [PATCH] x86/tdx: Generate SIGBUS on userspace MMIO
Currently attempt to do MMIO from userspace in TDX guest leads to
warning about unexpect #VE and SIGSEGV being delivered to the process.
Enlightened userspace might choose to deal with MMIO on their own if
kernel doesn't emulate it.
Handle EPT_VIOLATION exit reason for userspace and deliver SIGBUS
instead of SIGSEV. SIGBUS is more appropriate for MMIO situation.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
arch/x86/coco/tdx/tdx.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index c1cb90369915..d2aa93cebf5a 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -7,6 +7,7 @@
#include <linux/cpufeature.h>
#include <linux/export.h>
#include <linux/io.h>
+#include <linux/sched/signal.h>
#include <asm/coco.h>
#include <asm/tdx.h>
#include <asm/vmx.h>
@@ -630,6 +631,11 @@ void tdx_get_ve_info(struct ve_info *ve)
ve->instr_info = upper_32_bits(args.r10);
}
+static inline bool is_private_gpa(u64 gpa)
+{
+ return gpa == cc_mkenc(gpa);
+}
+
/*
* Handle the user initiated #VE.
*
@@ -641,17 +647,20 @@ static int virt_exception_user(struct pt_regs *regs, struct ve_info *ve)
switch (ve->exit_reason) {
case EXIT_REASON_CPUID:
return handle_cpuid(regs, ve);
+ case EXIT_REASON_EPT_VIOLATION:
+ if (is_private_gpa(ve->gpa))
+ panic("Unexpected EPT-violation on private memory.");
+
+ force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)ve->gla);
+
+ /* Return 0 to avoid incrementing RIP */
+ return 0;
default:
pr_warn("Unexpected #VE: %lld\n", ve->exit_reason);
return -EIO;
}
}
-static inline bool is_private_gpa(u64 gpa)
-{
- return gpa == cc_mkenc(gpa);
-}
-
/*
* Handle the kernel #VE.
*
--
2.43.0
Powered by blists - more mailing lists