On 2/1/2025 2:27 AM, Paolo Bonzini wrote:
On Fri, Jan 24, 2025 at 2:40 PM Xiaoyao Li <xiaoyao.li@xxxxxxxxx> wrote:
For TDX guest, the phys_bits is not configurable and can only be
host/native value.
Validate phys_bits inside tdx_check_features().
Hi Xiaoyao,
to avoid
qemu-kvm: TDX requires guest CPU physical bits (48) to match host CPU
physical bits (52)
I need options like
-cpu host,phys-bits=52,guest-phys-bits=52,host-phys-bits-limit=52,-kvm-asyncpf-int
to start a TDX guest, is that intentional?
"-cpu host" should be sufficient and should not hit the error.
why did you get "guest CPU physical bits (48)"?
Thanks,
Paolo
Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
---
target/i386/host-cpu.c | 2 +-
target/i386/host-cpu.h | 1 +
target/i386/kvm/tdx.c | 8 ++++++++
3 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/target/i386/host-cpu.c b/target/i386/host-cpu.c
index 3e4e85e729c8..8a15af458b05 100644
--- a/target/i386/host-cpu.c
+++ b/target/i386/host-cpu.c
@@ -15,7 +15,7 @@
#include "system/system.h"
/* Note: Only safe for use on x86(-64) hosts */
-static uint32_t host_cpu_phys_bits(void)
+uint32_t host_cpu_phys_bits(void)
{
uint32_t eax;
uint32_t host_phys_bits;
diff --git a/target/i386/host-cpu.h b/target/i386/host-cpu.h
index 6a9bc918baa4..b97ec01c9bec 100644
--- a/target/i386/host-cpu.h
+++ b/target/i386/host-cpu.h
@@ -10,6 +10,7 @@
#ifndef HOST_CPU_H
#define HOST_CPU_H
+uint32_t host_cpu_phys_bits(void);
void host_cpu_instance_init(X86CPU *cpu);
void host_cpu_max_instance_init(X86CPU *cpu);
bool host_cpu_realizefn(CPUState *cs, Error **errp);
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index bb75eb06dad9..c906a76c4c0e 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -24,6 +24,7 @@
#include "cpu.h"
#include "cpu-internal.h"
+#include "host-cpu.h"
#include "hw/i386/e820_memory_layout.h"
#include "hw/i386/x86.h"
#include "hw/i386/tdvf.h"
@@ -838,6 +839,13 @@ static int tdx_check_features(X86ConfidentialGuest *cg, CPUState *cs)
return -1;
}
+ if (cpu->phys_bits != host_cpu_phys_bits()) {
+ error_report("TDX requires guest CPU physical bits (%u) "
+ "to match host CPU physical bits (%u)",
+ cpu->phys_bits, host_cpu_phys_bits());
+ exit(1);
+ }
+
return 0;
}
--
2.34.1
