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From: Kuppuswamy Sathyanarayanan  <sathyanarayanan.kuppuswamy@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>
Cc: Peter H Anvin <hpa@zytor.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Kirill Shutemov <kirill.shutemov@linux.intel.com>,
	Sean Christopherson <seanjc@google.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v5 10/12] x86/tdx: Add MSR support for TDX guest
Date: Wed,  4 Aug 2021 11:13:27 -0700	[thread overview]
Message-ID: <20210804181329.2899708-11-sathyanarayanan.kuppuswamy@linux.intel.com> (raw)
In-Reply-To: <20210804181329.2899708-1-sathyanarayanan.kuppuswamy@linux.intel.com>

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

Operations on context-switched MSRs can be run natively. The rest of
MSRs should be handled through TDVMCALLs.

TDVMCALL[Instruction.RDMSR] and TDVMCALL[Instruction.WRMSR] provide
MSR oprations.

RDMSR and WRMSR specification details can be found in
Guest-Host-Communication Interface (GHCI) for Intel Trust Domain
Extensions (Intel TDX) specification, sec 3.10, 3.11.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---

Change since v4:
 * Removed You usage from commit log.

Changes since v3:
 * None

 arch/x86/kernel/tdx.c | 67 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index bdd041c4c509..d16c7f8759ea 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -104,6 +104,55 @@ static __cpuidle void tdg_safe_halt(void)
 	BUG_ON(ret);
 }
 
+static bool tdg_is_context_switched_msr(unsigned int msr)
+{
+	switch (msr) {
+	case MSR_EFER:
+	case MSR_IA32_CR_PAT:
+	case MSR_FS_BASE:
+	case MSR_GS_BASE:
+	case MSR_KERNEL_GS_BASE:
+	case MSR_IA32_SYSENTER_CS:
+	case MSR_IA32_SYSENTER_EIP:
+	case MSR_IA32_SYSENTER_ESP:
+	case MSR_STAR:
+	case MSR_LSTAR:
+	case MSR_SYSCALL_MASK:
+	case MSR_IA32_XSS:
+	case MSR_TSC_AUX:
+	case MSR_IA32_BNDCFGS:
+		return true;
+	}
+	return false;
+}
+
+static u64 tdg_read_msr_safe(unsigned int msr, int *err)
+{
+	u64 ret;
+	struct tdx_hypercall_output out = {0};
+
+	WARN_ON_ONCE(tdg_is_context_switched_msr(msr));
+
+	ret = _tdx_hypercall(EXIT_REASON_MSR_READ, msr, 0, 0, 0, &out);
+
+	*err = ret ? -EIO : 0;
+
+	return out.r11;
+}
+
+static int tdg_write_msr_safe(unsigned int msr, unsigned int low,
+			      unsigned int high)
+{
+	u64 ret;
+
+	WARN_ON_ONCE(tdg_is_context_switched_msr(msr));
+
+	ret = _tdx_hypercall(EXIT_REASON_MSR_WRITE, msr, (u64)high << 32 | low,
+			     0, 0, NULL);
+
+	return ret ? -EIO : 0;
+}
+
 unsigned long tdg_get_ve_info(struct ve_info *ve)
 {
 	u64 ret;
@@ -130,19 +179,33 @@ unsigned long tdg_get_ve_info(struct ve_info *ve)
 int tdg_handle_virtualization_exception(struct pt_regs *regs,
 					struct ve_info *ve)
 {
+	unsigned long val;
+	int ret = 0;
+
 	switch (ve->exit_reason) {
 	case EXIT_REASON_HLT:
 		tdg_halt();
 		break;
+	case EXIT_REASON_MSR_READ:
+		val = tdg_read_msr_safe(regs->cx, (unsigned int *)&ret);
+		if (!ret) {
+			regs->ax = val & UINT_MAX;
+			regs->dx = val >> 32;
+		}
+		break;
+	case EXIT_REASON_MSR_WRITE:
+		ret = tdg_write_msr_safe(regs->cx, regs->ax, regs->dx);
+		break;
 	default:
 		pr_warn("Unexpected #VE: %lld\n", ve->exit_reason);
 		return -EFAULT;
 	}
 
 	/* After successful #VE handling, move the IP */
-	regs->ip += ve->instr_len;
+	if (!ret)
+		regs->ip += ve->instr_len;
 
-	return 0;
+	return ret;
 }
 
 void __init tdx_early_init(void)
-- 
2.25.1


  parent reply	other threads:[~2021-08-04 18:15 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-04 18:13 [PATCH v5 00/12] Add TDX Guest Support (Initial support) Kuppuswamy Sathyanarayanan
2021-08-04 18:13 ` [PATCH v5 01/12] x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT Kuppuswamy Sathyanarayanan
2021-08-12  7:18   ` Borislav Petkov
2021-08-12 17:17     ` Kuppuswamy, Sathyanarayanan
2021-08-17 12:50     ` Juergen Gross
2021-08-17 13:16       ` Kuppuswamy, Sathyanarayanan
2021-08-17 13:28         ` Juergen Gross
2021-08-17 13:39           ` Kuppuswamy, Sathyanarayanan
2021-08-17 13:47             ` Juergen Gross
2021-08-17 13:50               ` Kuppuswamy, Sathyanarayanan
2021-08-04 18:13 ` [PATCH v5 02/12] x86/tdx: Introduce INTEL_TDX_GUEST config option Kuppuswamy Sathyanarayanan
2021-08-04 18:13 ` [PATCH v5 03/12] x86/cpufeatures: Add TDX Guest CPU feature Kuppuswamy Sathyanarayanan
2021-08-12  7:39   ` Borislav Petkov
2021-08-04 18:13 ` [PATCH v5 04/12] x86/tdx: Add protected guest support for TDX guest Kuppuswamy Sathyanarayanan
2021-08-04 21:59   ` Sean Christopherson
2021-08-04 22:03     ` Dave Hansen
2021-08-04 22:26       ` Kuppuswamy, Sathyanarayanan
2021-08-04 22:42         ` Sean Christopherson
2021-08-04 23:00           ` Kuppuswamy, Sathyanarayanan
2021-08-12  7:53             ` Borislav Petkov
2021-08-12 17:18               ` Kuppuswamy, Sathyanarayanan
2021-08-20 14:28                 ` Borislav Petkov
2021-08-20 16:42                   ` Kuppuswamy, Sathyanarayanan
2021-08-20 16:59                     ` Borislav Petkov
2021-08-20 17:11                       ` Kuppuswamy, Sathyanarayanan
2021-08-04 18:13 ` [PATCH v5 05/12] x86/tdx: Add __tdx_module_call() and __tdx_hypercall() helper functions Kuppuswamy Sathyanarayanan
2021-08-20 15:16   ` Borislav Petkov
2021-08-04 18:13 ` [PATCH v5 06/12] x86/tdx: Get TD execution environment information via TDINFO Kuppuswamy Sathyanarayanan
2021-08-04 22:38   ` Sean Christopherson
2021-08-20 17:13   ` Borislav Petkov
2021-08-20 17:31     ` Kuppuswamy, Sathyanarayanan
2021-08-20 17:35       ` Borislav Petkov
2021-08-20 18:29         ` Kuppuswamy, Sathyanarayanan
2021-08-20 18:58           ` Andi Kleen
2021-08-20 19:01             ` Kuppuswamy, Sathyanarayanan
2021-08-04 18:13 ` [PATCH v5 07/12] x86/traps: Add #VE support for TDX guest Kuppuswamy Sathyanarayanan
2021-08-24 10:17   ` Borislav Petkov
2021-08-24 17:32     ` Kuppuswamy, Sathyanarayanan
2021-08-24 17:36       ` Dave Hansen
2021-08-24 17:46       ` Borislav Petkov
2021-09-02 15:24         ` Kuppuswamy, Sathyanarayanan
2021-09-03 10:17           ` Borislav Petkov
2021-08-04 18:13 ` [PATCH v5 08/12] x86/tdx: Add HLT " Kuppuswamy Sathyanarayanan
2021-08-24 16:10   ` Borislav Petkov
2021-08-24 17:06     ` Sean Christopherson
2021-08-24 17:25       ` Andi Kleen
2021-08-24 17:27       ` Borislav Petkov
2021-08-24 17:47         ` Sean Christopherson
2021-08-24 17:50           ` Borislav Petkov
2021-08-31 20:49         ` Kuppuswamy, Sathyanarayanan
2021-09-01  7:42           ` Borislav Petkov
2021-08-24 18:18       ` Kuppuswamy, Sathyanarayanan
2021-08-24 18:28         ` Andi Kleen
2021-08-24 17:35     ` Kuppuswamy, Sathyanarayanan
2021-08-24 17:48       ` Borislav Petkov
2021-08-04 18:13 ` [PATCH v5 09/12] x86/tdx: Wire up KVM hypercalls Kuppuswamy Sathyanarayanan
2021-08-24 16:34   ` Borislav Petkov
2021-08-24 18:11     ` Kuppuswamy, Sathyanarayanan
2021-08-24 18:29       ` Borislav Petkov
2021-08-24 19:11         ` Kuppuswamy, Sathyanarayanan
2021-08-24 19:39           ` Borislav Petkov
2021-08-04 18:13 ` Kuppuswamy Sathyanarayanan [this message]
2021-08-24 16:55   ` [PATCH v5 10/12] x86/tdx: Add MSR support for TDX guest Borislav Petkov
2021-08-24 18:12     ` Kuppuswamy, Sathyanarayanan
2021-08-04 18:13 ` [PATCH v5 11/12] x86/tdx: Don't write CSTAR MSR on Intel Kuppuswamy Sathyanarayanan
2021-08-04 18:31   ` Sean Christopherson
2021-08-04 21:03     ` Kuppuswamy, Sathyanarayanan
2021-08-04 21:44       ` Sean Christopherson
2021-08-04 21:48       ` Dave Hansen
2021-08-04 22:23         ` Kuppuswamy, Sathyanarayanan
2021-08-04 18:13 ` [PATCH v5 12/12] x86/tdx: Handle CPUID via #VE Kuppuswamy Sathyanarayanan
2021-08-24 17:48   ` Borislav Petkov

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